"The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure" provides a new guideline for hypertension prevention and management. The following are the key messages(<em>1</em>) In persons older than 50 years, systolic blood pressure (BP) of more than <em>1</em>40 mm Hg is a much more important cardiovascular disease (CVD) risk factor than diastolic BP; (2) The risk of CVD, beginning at <em>1</em><em>1</em>5/<em>7</em>5 mm Hg, doubles with each increment of 20/<em>1</em>0 mm Hg; individuals who are normotensive at 55 years of age have a 90% lifetime risk for developing hypertension; (3) Individuals with a systolic BP of <em>1</em>20 to <em>1</em>39 mm Hg or a diastolic BP of 80 to 89 mm Hg should be considered as prehypertensive and require health-promoting lifestyle modifications to prevent CVD; (4) Thiazide-type diuretics should be used in drug treatment for most patients with uncomplicated hypertension, either alone or combined with drugs from other classes. Certain high-risk conditions are compelling indications for the initial use of other antihypertensive drug classes (<em>angiotensin</em>-converting enzyme inhibitors, <em>angiotensin</em>-receptor blockers, beta-blockers, calcium channel blockers); (5) Most patients with hypertension will require 2 or more antihypertensive medications to achieve goal BP ((<em>1</em>40/90 mm Hg, or (<em>1</em>30/80 mm Hg for patients with diabetes or chronic kidney disease); (6) If BP is more than 20/<em>1</em>0 mm Hg above goal BP, consideration should be given to initiating therapy with 2 agents, <em>1</em> of which usually should be a thiazide-type diuretic; and (<em>7</em>) The most effective therapy prescribed by the most careful clinician will control hypertension only if patients are motivated. Motivation improves when patients have positive experiences with and trust in the clinician. Empathy builds trust and is a potent motivator. Finally, in presenting these guidelines, the committee recognizes that the responsible physician's judgment remains paramount.

BACKGROUND

Hypertension is a leading cause of end-stage renal disease (ESRD) in the United States, with no known treatment to prevent progressive declines leading to ESRD.

OBJECTIVE

To compare the effects of 2 levels of blood pressure (BP) control and 3 antihypertensive drug classes on glomerular filtration rate (GFR) decline in hypertension.

METHODS

Randomized 3 x 2 factorial trial with enrollment from February <em>1</em>995 to September <em>1</em>998.

METHODS

A total of <em>1</em>094 African Americans aged <em>1</em>8 to 70 years with hypertensive renal disease (GFR, 20-65 mL/min per <em>1</em>.73 m(2)) were recruited from 2<em>1</em> clinical centers throughout the United States and followed up for 3 to 6.4 years.

METHODS

Participants were randomly assigned to <em>1</em> of 2 mean arterial pressure goals, <em>1</em>02 to <em>1</em>07 mm Hg (usual; n = 554) or 92 mm Hg or less (lower; n = 540), and to initial treatment with either a beta-blocker (metoprolol 50-200 mg/d; n = 44<em>1</em>), an <em>angiotensin</em>-converting enzyme inhibitor (ramipril 2.5-<em>1</em>0 mg/d; n = 436) or a dihydropyridine calcium channel blocker, (amlodipine 5-<em>1</em>0 mg/d; n = 2<em>1</em>7). Open-label agents were added to achieve the assigned BP goals.

METHODS

Rate of change in GFR (GFR slope); clinical composite outcome of reduction in GFR by 50% or more (or>> or =25 mL/min per <em>1</em>.73 m2) from baseline, ESRD, or death. Three primary treatment comparisons were specified: lower vs usual BP goal; ramipril vs metoprolol; and amlodipine vs metoprolol.

RESULTS

Achieved BP averaged (SD) <em>1</em>28/78 (<em>1</em>2/8) mm Hg in the lower BP group and <em>1</em>4<em>1</em>/85 (<em>1</em>2/7) mm Hg in the usual BP group. The mean (SE) GFR slope from baseline through 4 years did not differ significantly between the lower BP group (-2.2<em>1</em> [0.<em>1</em>7] mL/min per <em>1</em>.73 m2 per year) and the usual BP group (-<em>1</em>.95 [0.<em>1</em>7] mL/min per <em>1</em>.73 m2 per year; P =.24), and the lower BP goal did not significantly reduce the rate of the clinical composite outcome (risk reduction for lower BP group = 2%; 95% confidence interval [CI], -22% to 2<em>1</em>%; P =.85). None of the drug group comparisons showed consistent significant differences in the GFR slope. However, compared with the metoprolol and amlodipine groups, the ramipril group manifested risk reductions in the clinical composite outcome of 22% (95% CI, <em>1</em>%-38%; P =.04) and 38% (95% CI, <em>1</em>4%-56%; P =.004), respectively. There was no significant difference in the clinical composite outcome between the amlodipine and metoprolol groups.

CONCLUSIONS

No additional benefit of slowing progression of hypertensive nephrosclerosis was observed with the lower BP goal. Angiotensin-converting enzyme inhibitors appear to be more effective than beta-blockers or dihydropyridine calcium channel blockers in slowing GFR decline.

The renin-<em>angiotensin</em> system plays a critical role in blood pressure control and body fluid and electrolyte homeostasis. Besides <em>angiotensin</em> (Ang) II, other Ang peptides, such as Ang III [Ang-(2-8)], Ang IV [Ang-(3-8)], and Ang-(<em>1</em>-<em>7</em>) may also have important biological activities. Ang-(<em>1</em>-<em>7</em>) has become an <em>angiotensin</em> of interest in the past few years, because its cardiovascular and baroreflex actions counteract those of Ang II. Unique <em>angiotensin</em>-binding sites specific for this heptapeptide and studies with a selective Ang-(<em>1</em>-<em>7</em>) antagonist indicated the existence of a distinct Ang-(<em>1</em>-<em>7</em>) receptor. We demonstrate that genetic deletion of the G protein-coupled receptor encoded by the Mas protooncogene abolishes the binding of Ang-(<em>1</em>-<em>7</em>) to mouse kidneys. Accordingly, Mas-deficient mice completely lack the antidiuretic action of Ang-(<em>1</em>-<em>7</em>) after an acute water load. Ang-(<em>1</em>-<em>7</em>) binds to Mas-transfected cells and elicits arachidonic acid release. Furthermore, Mas-deficient aortas lose their Ang-(<em>1</em>-<em>7</em>)-induced relaxation response. Collectively, these findings identify Mas as a functional receptor for Ang-(<em>1</em>-<em>7</em>) and provide a clear molecular basis for the physiological actions of this biologically active peptide.

BACKGROUND

<em>Angiotensin</em>-converting enzyme 2 (ACE2) has emerged as a novel regulator of cardiac function and arterial pressure by converting <em>angiotensin</em> II (Ang II) into the vasodilator and antitrophic heptapeptide, <em>angiotensin</em>-(<em>1</em>-<em>7</em>) [Ang-(<em>1</em>-<em>7</em>)]. As the only known human homolog of ACE, the demonstration that ACE2 is insensitive to blockade by ACE inhibitors prompted us to define the effect of ACE inhibition on the ACE2 gene.

RESULTS

Blood pressure, cardiac rate, and plasma and cardiac tissue levels of Ang II and Ang-(<em>1</em>-<em>7</em>), together with cardiac ACE2, neprilysin, Ang II type <em>1</em> receptor (AT<em>1</em>), and mas receptor mRNAs, were measured in Lewis rats <em>1</em>2 days after continuous administration of vehicle, lisinopril, losartan, or both drugs combined in their drinking water. Equivalent decreases in blood pressure were obtained in rats given lisinopril or losartan alone or in combination. ACE inhibitor therapy caused a <em>1</em>.8-fold increase in plasma Ang-(<em>1</em>-<em>7</em>), decreased plasma Ang II, and increased cardiac ACE2 mRNA but not cardiac ACE2 activity. Losartan increased plasma levels of both Ang II and Ang-(<em>1</em>-<em>7</em>), as well as cardiac ACE2 mRNA and cardiac ACE2 activity. Combination therapy duplicated the effects found in rats medicated with lisinopril, except that cardiac ACE2 mRNA fell to values found in vehicle-treated rats. Losartan treatment but not lisinopril increased cardiac tissue levels of Ang II and Ang-(<em>1</em>-<em>7</em>), whereas none of the treatments had an effect on cardiac neprilysin mRNA.

CONCLUSIONS

Selective blockade of either Ang II synthesis or activity induced increases in cardiac ACE2 gene expression and cardiac ACE2 activity, whereas the combination of losartan and lisinopril was associated with elevated cardiac ACE2 activity but not cardiac ACE2 mRNA. Although the predominant effect of ACE inhibition may result from the combined effect of reduced Ang II formation and Ang-(<em>1</em>-<em>7</em>) metabolism, the antihypertensive action of AT<em>1</em> antagonists may in part be due to increased Ang II metabolism by ACE2.

Diabetic nephropathy is the leading cause of kidney disease in patients starting renal replacement therapy and affects approximately 40% of type <em>1</em> and type 2 diabetic patients. It increases the risk of death, mainly from cardiovascular causes, and is defined by increased urinary albumin excretion (UAE) in the absence of other renal diseases. Diabetic nephropathy is categorized into stages: microalbuminuria (UAE >20 microg/min and < or =<em>1</em>99 microg/min) and macroalbuminuria (UAE>> or =200 microg/min). Hyperglycemia, increased blood pressure levels, and genetic predisposition are the main risk factors for the development of diabetic nephropathy. Elevated serum lipids, smoking habits, and the amount and origin of dietary protein also seem to play a role as risk factors. Screening for microalbuminuria should be performed yearly, starting 5 years after diagnosis in type <em>1</em> diabetes or earlier in the presence of puberty or poor metabolic control. In patients with type 2 diabetes, screening should be performed at diagnosis and yearly thereafter. Patients with micro- and macroalbuminuria should undergo an evaluation regarding the presence of comorbid associations, especially retinopathy and macrovascular disease. Achieving the best metabolic control (A<em>1</em>c (<em>7</em>%), treating hypertension ((<em>1</em>30/80 mmHg or (<em>1</em>25/<em>7</em>5 mmHg if proteinuria>><em>1</em>.0 g/24 h and increased serum creatinine), using drugs with blockade effect on the renin-<em>angiotensin</em>-aldosterone system, and treating dyslipidemia (LDL cholesterol (<em>1</em>00 mg/dl) are effective strategies for preventing the development of microalbuminuria, in delaying the progression to more advanced stages of nephropathy and in reducing cardiovascular mortality in patients with type <em>1</em> and type 2 diabetes.

<em>Angiotensin</em>-converting enzyme (ACE2) has a multiplicity of physiological roles that revolve around its trivalent function: a negative regulator of the renin-<em>angiotensin</em> system (RAS), facilitator of amino acid transport, and the SARS-CoV and SARS-CoV-2 receptor. ACE2 is widely expressed, including, in the lungs, cardiovascular system, gut, kidneys, central nervous system, and adipose tissue. ACE2 has recently been identified as the SARS-CoV-2 receptor, the infective agent responsible for COVID-<em>1</em>9, providing a critical link between immunity, inflammation, ACE2, and cardiovascular disease. Although sharing a close evolutionary relationship with SARS-CoV, the receptor-binding domain of SARS-CoV-2 differs in several key amino acid residues, allowing for stronger binding affinity with the human ACE2 receptor, which may account for the greater pathogenicity of SARS-CoV-2. The loss of ACE2 function following binding by SARS-CoV-2 is driven by endocytosis and activation of proteolytic cleavage and processing. The ACE2 system is a critical protective pathway against heart failure with reduced and preserved ejection fraction including, myocardial infarction and hypertension, and against lung disease and diabetes. The control of gut dysbiosis and vascular permeability by ACE2 has emerged as an essential mechanism of pulmonary hypertension and diabetic cardiovascular complications. Recombinant ACE2, gene-delivery of Ace2, Ang <em>1</em>-<em>7</em> analogs, and Mas receptor agonists enhance ACE2 action and serve as potential therapies for disease conditions associated with an activated RAS. Recombinant human ACE2 has completed clinical trials and efficiently lowered or increased plasma <em>angiotensin</em> II and <em>angiotensin</em> <em>1</em>-<em>7</em> levels, respectively. Our review summarizes the progress over the past 20 years, highlighting the critical role of ACE2 as the novel SARS-CoV-2 receptor and as the negative regulator of the RAS, together with implications for the COVID-<em>1</em>9 pandemic and associated cardiovascular diseases.

Using both confocal immunofluorescence microscopy and biochemical approaches, we have examined the role of beta-arrestins in the activation and targeting of extracellular signal-regulated kinase 2 (ERK2) following stimulation of <em>angiotensin</em> II type <em>1</em>a receptors (AT<em>1</em>aR). In HEK-293 cells expressing hemagglutinin-tagged AT<em>1</em>aR, <em>angiotensin</em> stimulation triggered beta-arrestin-2 binding to the receptor and internalization of AT<em>1</em>aR-beta-arrestin complexes. Using red fluorescent protein-tagged ERK2 to track the subcellular distribution of ERK2, we found that <em>angiotensin</em> treatment caused the redistribution of activated ERK2 into endosomal vesicles that also contained AT<em>1</em>aR-beta-arrestin complexes. This targeting of ERK2 reflects the formation of multiprotein complexes containing AT<em>1</em>aR, beta-arrestin-2, and the component kinases of the ERK cascade, cRaf-<em>1</em>, MEK<em>1</em>, and ERK2. Myc-tagged cRaf-<em>1</em>, MEK<em>1</em>, and green fluorescent protein-tagged ERK2 coprecipitated with Flag-tagged beta-arrestin-2 from transfected COS-<em>7</em> cells. Coprecipitation of cRaf-<em>1</em> with beta-arrestin-2 was independent of MEK<em>1</em> and ERK2, whereas the coprecipitation of MEK<em>1</em> and ERK2 with beta-arrestin-2 was significantly enhanced in the presence of overexpressed cRaf-<em>1</em>, suggesting that binding of cRaf-<em>1</em> to beta-arrestin facilitates the assembly of a cRaf-<em>1</em>, MEK<em>1</em>, ERK2 complex. The phosphorylation of ERK2 in beta-arrestin complexes was markedly enhanced by coexpression of cRaf-<em>1</em>, and this effect is blocked by expression of a catalytically inactive dominant inhibitory mutant of MEK<em>1</em>. Stimulation with <em>angiotensin</em> increased the binding of both cRaf-<em>1</em> and ERK2 to beta-arrestin-2, and the association of beta-arrestin-2, cRaf-<em>1</em>, and ERK2 with AT<em>1</em>aR. These data suggest that beta-arrestins function both as scaffolds to enhance cRaf-<em>1</em> and MEK-dependent activation of ERK2, and as targeting proteins that direct activated ERK to specific subcellular locations.

beta-Arrestins, originally discovered in the context of heterotrimeric guanine nucleotide binding protein-coupled receptor (GPCR) desensitization, also function in internalization and signaling of these receptors. We identified c-Jun amino-terminal kinase 3 (JNK3) as a binding partner of beta-arrestin 2 using a yeast two-hybrid screen and by coimmunoprecipitation from mouse brain extracts or cotransfected COS-<em>7</em> cells. The upstream JNK activators apoptosis signal-regulating kinase <em>1</em> (ASK<em>1</em>) and mitogen-activated protein kinase (MAPK) kinase 4 were also found in complex with beta-arrestin 2. Cellular transfection of beta-arrestin 2 caused cytosolic retention of JNK3 and enhanced JNK3 phosphorylation stimulated by ASK<em>1</em>. Moreover, stimulation of the <em>angiotensin</em> II type <em>1</em>A receptor activated JNK3 and triggered the colocalization of beta-arrestin 2 and active JNK3 to intracellular vesicles. Thus, beta-arrestin 2 acts as a scaffold protein, which brings the spatial distribution and activity of this MAPK module under the control of a GPCR.

We previously reported enhanced expression of the p6<em>7</em>(phox) and gp9<em>1</em>(phox) components of NAD(P)H oxidase in <em>angiotensin</em> (Ang) II-induced hypertension, suggesting de novo assembly in response to Ang II. To examine the direct involvement of NAD(P)H oxidases in Ang II-induced O(2)(-) production, we designed a chimeric peptide that inhibits p4<em>7</em>(phox) association with gp9<em>1</em>(phox) in NAD(P)H oxidase (gp9<em>1</em>ds-tat). This was achieved by linking a 9-amino acid peptide (aa) derived from HIV-coat protein (tat) to a 9-aa sequence of gp9<em>1</em>(phox) (known to interact with p4<em>7</em>(phox)). As a control, we constructed a chimera containing tat and a scrambled gp9<em>1</em> sequence (scramb-tat). We found that gp9<em>1</em>ds-tat decreased O(2)(-) levels in aortic rings treated with Ang II (<em>1</em>0 pmol/L) but had no effect on either the O(2)(-)-generating enzyme xanthine oxidase or potassium superoxide-generated O(2)(-). We infused vehicle, Ang II (0.<em>7</em>5 mg. kg(-<em>1</em>). d(-<em>1</em>)), Ang II+gp9<em>1</em>ds-tat (<em>1</em>0 mg. kg(-<em>1</em>). d(-<em>1</em>)), or Ang II+scramb-tat intraperitoneally in C5<em>7</em>Bl/6 mice and measured systolic blood pressure (SBP) on days 0, 3, 5, and <em>7</em> of infusion. SBP increased by day 3 in mice given Ang II and Ang II+scramb-tat but was significantly lower with Ang II+gp9<em>1</em>-tat. On day <em>7</em>, SBP was still significantly inhibited in mice given Ang II+gp9<em>1</em>ds-tat, whereas Ang II-induced O(2)(-) production was inhibited throughout the aorta as detected by dihydroethidium staining, consistent with the ability of this inhibitor to block the various vascular NAD(P)H oxidase isoforms. These data support the hypothesis that inhibition of the interaction of p4<em>7</em>(phox) and gp9<em>1</em>(phox) (or its homologues) can block O(2)(-) production and attenuate blood pressure elevation in mice.

In the stressed animal, the vasoactive hormones vasopressin and <em>angiotensin</em>-II and the neurotransmitter noradrenaline induce liver cells to release glucose from glycogen. The intracellular signal that links the cell-surface receptors for noradrenaline (alpha <em>1</em>) and vasoactive peptides to activation of glycogenolysis is known to be a rise in the cytoplasmic concentration of free calcium ions (free Ca). The receptors for these agonists induce the hydrolysis of phosphatidylinositol 4,5-bisphosphate, a minor plasmalemma lipid, to produce inositol trisphosphate and diacylglycerol. Inositol trisphosphate has been shown to mobilize intracellular calcium in hepatocytes. We show here, by means of aequorin measurements in single, isolated rat hepatocytes, that the free Ca response to these agonists consists of a series of transients. Each transient rose within 3 s to a peak free Ca of at least 600 nM and had a duration of approximately <em>7</em> s. The transients were repeated at intervals of 0.3-4 min, depending on agonist concentration. Between transients, free Ca returned to the resting level of approximately 200 nM. Clearly, the mechanisms controlling free Ca in hepatocytes are more complex than hitherto suspected.

<em>Angiotensin</em> converting enzyme-2 (ACE2) receptors mediate the entry into the cell of three strains of coronavirus: SARS-CoV, NL63 and SARS-CoV-2. ACE2 receptors are ubiquitous and widely expressed in the heart, vessels, gut, lung (particularly in type 2 pneumocytes and macrophages), kidney, testis and brain. ACE2 is mostly bound to cell membranes and only scarcely present in the circulation in a soluble form. An important salutary function of membrane-bound and soluble ACE2 is the degradation of <em>angiotensin</em> II to <em>angiotensin</em>_{<em>1</em>-<em>7</em>}. Consequently, ACE2 receptors limit several detrimental effects resulting from binding of <em>angiotensin</em> II to AT<em>1</em> receptors, which include vasoconstriction, enhanced inflammation and thrombosis. The increased generation of <em>angiotensin</em>_{<em>1</em>-<em>7</em>} also triggers counter-regulatory protective effects through binding to G-protein coupled Mas receptors. Unfortunately, the entry of SARS-CoV2 into the cells through membrane fusion markedly down-regulates ACE2 receptors, with loss of the catalytic effect of these receptors at the external site of the membrane. Increased pulmonary inflammation and coagulation have been reported as unwanted effects of enhanced and unopposed <em>angiotensin</em> II effects via the ACE→<em>Angiotensin</em> II→AT<em>1</em> receptor axis. Clinical reports of patients infected with SARS-CoV-2 show that several features associated with infection and severity of the disease (i.e., older age, hypertension, diabetes, cardiovascular disease) share a variable degree of ACE2 deficiency. We suggest that ACE2 down-regulation induced by viral invasion may be especially detrimental in people with baseline ACE2 deficiency associated with the above conditions. The additional ACE2 deficiency after viral invasion might amplify the dysregulation between the 'adverse' ACE→<em>Angiotensin</em> II→AT<em>1</em> receptor axis and the 'protective' ACE2→<em>Angiotensin</em>_{<em>1</em>-<em>7</em>}→Mas receptor axis. In the lungs, such dysregulation would favor the progression of inflammatory and thrombotic processes triggered by local <em>angiotensin</em> II hyperactivity unopposed by <em>angiotensin</em>_{<em>1</em>-<em>7</em>}. In this setting, recombinant ACE2, <em>angiotensin</em>_{<em>1</em>-<em>7</em>} and <em>angiotensin</em> II type <em>1</em> receptor blockers could be promising therapeutic approaches in patients with SARS-CoV-2 infection.

BACKGROUND

Although most cardiovascular disease occurs in low-income and middle-income countries, little is known about the use of effective secondary prevention medications in these communities. We aimed to assess use of proven effective secondary preventive drugs (antiplatelet drugs, β blockers, angiotensin-converting-enzyme [ACE] inhibitors or angiotensin-receptor blockers [ARBs], and statins) in individuals with a history of coronary heart disease or stroke.

METHODS

In the Prospective Urban Rural Epidemiological (PURE) study, we recruited individuals aged 35-70 years from rural and urban communities in countries at various stages of economic development. We assessed rates of previous cardiovascular disease (coronary heart disease or stroke) and use of proven effective secondary preventive drugs and blood-pressure-lowering drugs with standardised questionnaires, which were completed by telephone interviews, household visits, or on patient's presentation to clinics. We report estimates of drug use at national, community, and individual levels.

RESULTS

We enrolled 153,996 adults from 628 urban and rural communities in countries with incomes classified as high (three countries), upper-middle (seven), lower-middle (three), or low (four) between January, 2003, and December, 2009. 5650 participants had a self-reported coronary heart disease event (median 5·0 years previously [IQR 2·0-10·0]) and 2292 had stroke (4·0 years previously [2·0-8·0]). Overall, few individuals with cardiovascular disease took antiplatelet drugs (25·3%), β blockers (17·4%), ACE inhibitors or ARBs (19·5%), or statins (14·6%). Use was highest in high-income countries (antiplatelet drugs 62·0%, β blockers 40·0%, ACE inhibitors or ARBs 49·8%, and statins 66·5%), lowest in low-income countries (8·8%, 9·7%, 5·2%, and 3·3%, respectively), and decreased in line with reduction of country economic status (p(trend)<0·0001 for every drug type). Fewest patients received no drugs in high-income countries (11·2%), compared with 45·1% in upper middle-income countries, 69·3% in lower middle-income countries, and 80·2% in low-income countries. Drug use was higher in urban than rural areas (antiplatelet drugs 28·7% urban vs 21·3% rural, β blockers 23·5%vs 15·6%, ACE inhibitors or ARBs 22·8%vs 15·5%, and statins 19·9%vs 11·6%; all p<0·0001), with greatest variation in poorest countries (p(interaction)<0·0001 for urban vs rural differences by country economic status). Country-level factors (eg, economic status) affected rates of drug use more than did individual-level factors (eg, age, sex, education, smoking status, body-mass index, and hypertension and diabetes statuses).

CONCLUSIONS

Because use of secondary prevention medications is low worldwide-especially in low-income countries and rural areas-systematic approaches are needed to improve the long-term use of basic, inexpensive, and effective drugs.

BACKGROUND

Full funding sources listed at end of paper (see Acknowledgments).

<em>1</em>. Strips of longitudinal muscle can be obtained from guinea-pig ileum either retaining or free from Auerbach's plexus.2. The denervated strip is unresponsive to electrical stimulation by brief shocks, whether given singly or in trains; it also fails to respond to nicotine or dimethylphenylpiperazinium iodide (DMPP), and eserine causes no spasm.3. Denervated strips neither contain detectable acetylcholine (< 0.4 ng/mg), nor release it spontaneously (< 5 pg/mg/min) or in response to stimulation (< 3<em>1</em> pg/mg/min). The acetylcholine metabolism of the innervated strip is therefore that of the adherent Auerbach's plexus. Innervated strips had a mean acetylcholine content of 28 ng/mg, a mean resting output of 94 pg/mg/min and an output in response to stimulation at <em>1</em>0 c/s of <em>7</em>00-<em>1</em>200 pg/mg/min.4. By comparing the responses of innervated and denervated strips it was concluded that arecoline, methylfurmethide, alpha,beta-ethylal-gamma-tri-methylammonium propanediol iodide (2268 F), muscarine, histamine, tremorine, oxytocin, and substance P, like acetylcholine, act primarily on the smooth muscle directly; and that <em>angiotensin</em>, barium, potassium, m-bromophenyl choline ether and 5-hydroxytryptamine have a progressively increasing proportionate effect on the nerve plexus. Nicotine and DMPP were inactive in the absence of the plexus.5. The longitudinal muscle with its accompanying plexus contains about one quarter of the acetylcholine of the whole ileum, and is responsible for about one fifth of the output to electrical stimulation.6. The volley output of acetylcholine by the innervated strip declines sharply as rate of stimulation increases. Output of acetylcholine was reduced by morphine and by cocaine, particularly when resting or when stimulated at low rates.<em>7</em>. Acetylcholine output by whole ileum from guinea-pig declines in the absence of glucose, but is insulin-independent. Output by strips of ileum from rats made diabetic with alloxan was similar to that from normal rats.8. The similarity in properties of acetylcholine output from innervated strips, where it must come from nervous tissue, to that from whole ileum, and the insulin-independence of output from whole ileum suggest that the whole of the acetylcholine output of intestine is nervous in origin.9. Comparison of the acetylcholine metabolism of the innervated strip with that of the superior cervical ganglion suggests that the typical features of the former (high resting output, high volley output at low rates, low minute output at high rates of stimulation, and sensitivity to morphine) may be linked with the absence of specialized neuro-effector junctions and represent a relatively primitive transmission process.

The renin-<em>angiotensin</em>-aldosterone system has been causally implicated in obesity-associated hypertension. We studied the influence of obesity and weight reduction on the circulating and adipose tissue renin-<em>angiotensin</em>-aldosterone system in menopausal women. Blood samples were analyzed for <em>angiotensin</em>ogen, renin, aldosterone, <em>angiotensin</em>-converting enzyme activity, and <em>angiotensin</em> II. In adipose tissue biopsy samples, we analyzed <em>angiotensin</em>ogen, renin, renin-receptor, <em>angiotensin</em>-converting enzyme, and <em>angiotensin</em> II type-<em>1</em> receptor gene expression. Obese women (n=<em>1</em>9) had higher circulating <em>angiotensin</em>ogen, renin, aldosterone, and <em>angiotensin</em>-converting enzyme than lean women (n=<em>1</em>9), and lower <em>angiotensin</em>ogen gene expression in adipose tissue. Seventeen women successfully participated in a weight reduction protocol over <em>1</em>3 weeks to reduce daily caloric intake by 600 kcal. Body weight was reduced by -5%, as were <em>angiotensin</em>ogen levels by -2<em>7</em>%, renin by -43%, aldosterone by -3<em>1</em>%, <em>angiotensin</em>-converting enzyme activity by -<em>1</em>2%, and <em>angiotensin</em>ogen expression by -20% in adipose tissue (all P<0.05). The plasma <em>angiotensin</em>ogen decrease was highly correlated with the waist circumference decline (r=0.<em>7</em>4; P<0.00<em>1</em>). Weight and renin-<em>angiotensin</em>-aldosterone system reductions were accompanied by a -<em>7</em>-mm Hg reduced systolic ambulatory blood pressure. These data suggest that a 5% reduction in body weight can lead to a meaningfully reduced renin-<em>angiotensin</em>-aldosterone system in plasma and adipose tissue, which may contribute to the reduced blood pressure.

BACKGROUND

<em>Angiotensin</em> converting enzyme 2 (ACE2), a monocarboxylase that degrades <em>angiotensin</em> II to <em>angiotensin</em> <em>1</em>-<em>7</em>, is also the functional receptor for severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV) and is highly expressed in the lungs and heart. Patients with SARS also suffered from cardiac disease including arrhythmias, sudden cardiac death, and systolic and diastolic dysfunction.

METHODS

We studied mice infected with the human strain of the SARS-CoV and encephalomyocarditis virus and examined ACE2 mRNA and protein expression. Autopsy heart samples from patients who succumbed to the SARS crisis in Toronto (Canada) were used to investigate the impact of SARS on myocardial structure, inflammation and ACE2 protein expression.

RESULTS

Pulmonary infection with the human SARS-CoV in mice led to an ACE2-dependent myocardial infection with a marked decrease in ACE2 expression confirming a critical role of ACE2 in mediating SARS-CoV infection in the heart. The SARS-CoV viral RNA was detected in 35% (<em>7</em>/20) of autopsied human heart samples obtained from patients who succumbed to the SARS crisis during the Toronto SARS outbreak. Macrophage-specific staining showed a marked increase in macrophage infiltration with evidence of myocardial damage in patients who had SARS-CoV in their hearts. The presence of SARS-CoV in the heart was also associated with marked reductions in ACE2 protein expression.

CONCLUSIONS

Our data show that SARS-CoV can mediate myocardial inflammation and damage associated with down-regulation of myocardial ACE2 system, which may be responsible for the myocardial dysfunction and adverse cardiac outcomes in patients with SARS.

In the RAS (renin-<em>angiotensin</em> system), Ang I (<em>angiotensin</em> I) is cleaved by ACE (<em>angiotensin</em>-converting enzyme) to form Ang II (<em>angiotensin</em> II), which has effects on blood pressure, fluid and electrolyte homoeostasis. We have examined the kinetics of <em>angiotensin</em> peptide cleavage by full-length human ACE, the separate N- and C-domains of ACE, the homologue of ACE, ACE2, and NEP (neprilysin). The activity of the enzyme preparations was determined by active-site titrations using competitive tight-binding inhibitors and fluorogenic substrates. Ang I was effectively cleaved by NEP to Ang (<em>1</em>-<em>7</em>) (kcat/K(m) of 6.2x<em>1</em>0(5) M(-<em>1</em>) x s(-<em>1</em>)), but was a poor substrate for ACE2 (kcat/K(m) of 3.3x<em>1</em>0(4) M(-<em>1</em>) x s(-<em>1</em>)). Ang (<em>1</em>-9) was a better substrate for NEP than ACE (kcat/K(m) of 3.<em>7</em>x<em>1</em>0(5) M(-<em>1</em>) x s(-<em>1</em>) compared with kcat/K(m) of 6.8x<em>1</em>0(4) M(-<em>1</em>) x s(-<em>1</em>)). Ang II was cleaved efficiently by ACE2 to Ang (<em>1</em>-<em>7</em>) (kcat/K(m) of 2.2x<em>1</em>0(6) M(-<em>1</em>) x s(-<em>1</em>)) and was cleaved by NEP (kcat/K(m) of 2.2x<em>1</em>0(5) M(-<em>1</em>) x s(-<em>1</em>)) to several degradation products. In contrast with a previous report, Ang (<em>1</em>-<em>7</em>), like Ang I and Ang (<em>1</em>-9), was cleaved with a similar efficiency by both the N- and C-domains of ACE (kcat/K(m) of 3.6x<em>1</em>0(5) M(-<em>1</em>) x s(-<em>1</em>) compared with kcat/K(m) of 3.3x<em>1</em>0(5) M(-<em>1</em>) x s(-<em>1</em>)). The two active sites of ACE exhibited negative co-operativity when either Ang I or Ang (<em>1</em>-<em>7</em>) was the substrate. In addition, a range of ACE inhibitors failed to inhibit ACE2. These kinetic data highlight that the flux of peptides through the RAS is complex, with the levels of ACE, ACE2 and NEP dictating whether vasoconstriction or vasodilation will predominate.

BACKGROUND

Drug-drug interactions are a preventable cause of morbidity and mortality, yet their consequences in the community are not well characterized.

OBJECTIVE

To determine whether elderly patients admitted to hospital with specific drug toxicities were likely to have been prescribed an interacting drug in the week prior to admission.

METHODS

Three population-based, nested case-control studies.

METHODS

Ontario, Canada, from January <em>1</em>, <em>1</em>994, to December 3<em>1</em>, 2000.

METHODS

All Ontario residents aged 66 years or older treated with glyburide, digoxin, or an angiotensin-converting enzyme (ACE) inhibitor. Case patients were those admitted to hospital for drug-related toxicity. Prescription records of cases were compared with those of controls (matched on age, sex, use of the same medication, and presence or absence of renal disease) for receipt of interacting medications (co-trimoxazole with glyburide, clarithromycin with digoxin, and potassium-sparing diuretics with ACE inhibitors).

METHODS

Odds ratio for association between hospital admission for drug toxicity (hypoglycemia, digoxin toxicity, or hyperkalemia, respectively) and use of an interacting medication in the preceding week, adjusted for diagnoses, receipt of other medications, the number of prescription drugs, and the number of hospital admissions in the year preceding the index date.

RESULTS

During the 7-year study period, 909 elderly patients receiving glyburide were admitted with a diagnosis of hypoglycemia. In the primary analysis, those patients admitted for hypoglycemia were more than 6 times as likely to have been treated with co-trimoxazole in the previous week (adjusted odds ratio, 6.6; 95% confidence interval, 4.5-9.7). Patients admitted with digoxin toxicity (n = <em>1</em>05<em>1</em>) were about <em>1</em>2 times more likely to have been treated with clarithromycin (adjusted odds ratio, <em>1</em><em>1</em>.7; 95% confidence interval, 7.5-<em>1</em>8.2) in the previous week, and patients treated with ACE inhibitors admitted with a diagnosis of hyperkalemia (n = 523) were about 20 times more likely to have been treated with a potassium-sparing diuretic (adjusted odds ratio, 20.3; 95% confidence interval, <em>1</em>3.4-30.7) in the previous week. No increased risk of drug toxicity was found for drugs with similar indications but no known interactions (amoxicillin, cefuroxime, and indapamide, respectively).

CONCLUSIONS

Many hospital admissions of elderly patients for drug toxicity occur after administration of a drug known to cause drug-drug interactions. Many of these interactions could have been avoided.

BACKGROUND

ACE inhibitors attenuate the detrimental effects of <em>angiotensin</em> II, and improve survival and reduce morbidity in patients with acute myocardial infarction and evidence of heart failure or left-ventricular dysfunction. Selective antagonism of the <em>angiotensin</em> type <em>1</em> receptor represents an alternative approach to inhibition of the renin-<em>angiotensin</em> system. We did a multicentre, randomised trial to test the hypothesis that the <em>angiotensin</em> II antagonist losartan would be superior or non-inferior to the ACE inhibitor captopril in decreasing all-cause mortality in high-risk patients after acute myocardial infarction.

METHODS

5477 patients 50 years of age or older (mean age 67.4 years [SD 9.8]), with confirmed acute myocardial infarction and heart failure during the acute phase or a new Q-wave anterior infarction or reinfarction, were recruited from 329 centres in seven European countries. Patients were randomly assigned and titrated to a target dose of losartan (50 mg once daily) or captopril (50 mg three times daily) as tolerated. The primary endpoint was all-cause mortality. Analysis was by intention to treat.

RESULTS

There were 946 deaths during a mean follow-up of 2.7 (0.9) years: 499 (<em>1</em>8%) in the losartan group and 447 (<em>1</em>6%) in the captopril group (relative risk <em>1</em>.<em>1</em>3 [95% CI 0.99-<em>1</em>.28], p=0.07). The results for the secondary and tertiary endpoints were as follows: sudden cardiac death or resuscitated cardiac arrest 239 (9%) versus 203 (7%), <em>1</em>.<em>1</em>9 (0.98-<em>1</em>.43), p=0.07, and fatal or non-fatal reinfarction 384 (<em>1</em>4%) versus 379 (<em>1</em>4%), <em>1</em>.03 (0.89-<em>1</em>.<em>1</em>8), p=0.72. The all-cause hospital admission rates were <em>1</em>806 (66%) versus <em>1</em>774 (65%), <em>1</em>.03 (0.97-<em>1</em>.<em>1</em>0), p=0.37. Losartan was significantly better tolerated than captopril, with fewer patients discontinuing study medication (458 [<em>1</em>7%] vs 624 [23%], 0.70 [0.62-0.79], p<0.000<em>1</em>).

CONCLUSIONS

Since we saw a non-significant difference in total mortality in favour of captopril, ACE inhibitors should remain first-choice treatment in patients after complicated acute myocardial infarction. Losartan cannot be generally recommended in this population. However, it was better tolerated than captopril, and was associated with significantly fewer discontinuations. Although the role of losartan in patients intolerant of ACE inhibition is not clearly defined, it can be considered in such patients.

Glucagon-like peptide (GLP)-<em>1</em>-(<em>7</em>-36) amide and its pancreatic receptors are important for control of blood glucose levels. However, rat GLP-<em>1</em> receptors are also localized in the brain, in hypothalamus, and in areas without a blood-brain barrier. When rats were kept on a food restriction schedule, intracerebroventricular injection of GLP-<em>1</em> just before food was offered inhibited food intake. However, peripheral GLP-<em>1</em> administration by intraperitoneal injection had little effect. GLP-<em>1</em> effects on water intake and output were also investigated. Intracerebroventricular GLP-<em>1</em> profoundly inhibited <em>angiotensin</em> II-induced drinking behavior in rats, and water intake was suppressed by exogenous GLP-<em>1</em> in rats habituated to a water restriction schedule. These effects were reproduced by intraperitoneal administration of GLP-<em>1</em>. Furthermore, intracerebroventricular GLP-<em>1</em> stimulated urinary excretion of water and sodium. The centrally elicited effects were blocked by the GLP-<em>1</em> antagonist exendin-(9-39) amide, whereas the N-terminally extended and inactive GLP-<em>1</em>-(<em>1</em>-36) amide had no effect on feeding and drinking. GLP-<em>1</em> had no effect in behavioral assays measuring exploratory locomotor activity and conditioned taste aversion. In conclusion, GLP-<em>1</em> may play a physiological role in regulation of both ingestion and the water and salt homeostasis.

Heart failure (HF) remains the most common cause of death and disability, and a major economic burden, in industrialized nations. Physiological, pharmacological, and clinical studies have demonstrated that activation of the renin-<em>angiotensin</em> system is a key mediator of HF progression. <em>Angiotensin</em>-converting enzyme 2 (ACE2), a homolog of ACE, is a monocarboxypeptidase that converts <em>angiotensin</em> II into <em>angiotensin</em> <em>1</em>-<em>7</em> (Ang <em>1</em>-<em>7</em>) which, by virtue of its actions on the Mas receptor, opposes the molecular and cellular effects of <em>angiotensin</em> II. ACE2 is widely expressed in cardiomyocytes, cardiofibroblasts, and coronary endothelial cells. Recent preclinical translational studies confirmed a critical counter-regulatory role of ACE2/Ang <em>1</em>-<em>7</em> axis on the activated renin-<em>angiotensin</em> system that results in HF with preserved ejection fraction. Although loss of ACE2 enhances susceptibility to HF, increasing ACE2 level prevents and reverses the HF phenotype. ACE2 and Ang <em>1</em>-<em>7</em> have emerged as a key protective pathway against HF with reduced and preserved ejection fraction. Recombinant human ACE2 has been tested in phase I and II clinical trials without adverse effects while lowering and increasing plasma <em>angiotensin</em> II and Ang <em>1</em>-<em>7</em> levels, respectively. This review discusses the transcriptional and post-transcriptional regulation of ACE2 and the role of the ACE2/Ang <em>1</em>-<em>7</em> axis in cardiac physiology and in the pathophysiology of HF. The pharmacological and therapeutic potential of enhancing ACE2/Ang <em>1</em>-<em>7</em> action as a novel therapy for HF is highlighted.

<em>Angiotensin</em>-(<em>1</em>-<em>7</em>) [Ang-(<em>1</em>-<em>7</em>)] causes endothelial-dependent vasodilation mediated, in part, by NO release. However, the molecular mechanisms involved in endothelial NO synthase (eNOS) activation by Ang-(<em>1</em>-<em>7</em>) remain unknown. Using Chinese hamster ovary cells stably transfected with Mas cDNA (Chinese hamster ovary-Mas), we evaluated the underlying mechanisms related to receptor Mas-mediated posttranslational eNOS activation and NO release. We further examined the Ang-(<em>1</em>-<em>7</em>) profile of eNOS activation in human aortic endothelial cells, which constitutively express the Mas receptor. Chinese hamster ovary-Mas cells and human aortic endothelial cell were stimulated with Ang-(<em>1</em>-<em>7</em>; <em>1</em>0(-<em>7</em>) mol/L; <em>1</em> to 30 minutes) in the absence or presence of A-<em>7</em><em>7</em>9 (<em>1</em>0(-6) mol/L). Additional experiments were performed in the presence of the phosphatidylinositol 3-kinase inhibitor wortmannin (<em>1</em>0(-6) mol/L). Changes in eNOS (at Ser<em>1</em><em>1</em><em>7</em><em>7</em>/Thr495 residues) and Akt phosphorylation were evaluated by Western blotting. NO release was measured using both the fluorochrome 2,3-diaminonaphthalene and an NO analyzer. Ang-(<em>1</em>-<em>7</em>) significantly stimulated eNOS activation (reciprocal phosphorylation/dephosphorylation at Ser<em>1</em><em>1</em><em>7</em><em>7</em>/Thr495) and induced a sustained Akt phosphorylation (P<0.05). Concomitantly, a significant increase in NO release was observed (2-fold increase in relation to control). These effects were blocked by A-<em>7</em><em>7</em>9. Wortmannin suppressed eNOS activation in both Chinese hamster ovary-Mas and human aortic endothelial cells. Our findings demonstrate that Ang-(<em>1</em>-<em>7</em>), through Mas, stimulates eNOS activation and NO production via Akt-dependent pathways. These novel data highlight the importance of the Ang-(<em>1</em>-<em>7</em>)/Mas axis as a putative regulator of endothelial function.

The renin-<em>angiotensin</em> system (RAS) is a coordinated hormonal cascade in the control of cardiovascular, renal, and adrenal function that governs body fluid and electrolyte balance, as well as arterial pressure. The classical RAS consists of a circulating endocrine system in which the principal effector hormone is <em>angiotensin</em> (ANG) II. ANG is produced by the action of renin on <em>angiotensin</em>ogen to form ANG I and its subsequent conversion to the biologically active octapeptide by ANG-converting enzyme. ANG II actions are mediated via the ANG type <em>1</em> receptor. Here, we discuss recent advances in our understanding of the components and actions of the RAS, including local tissue RASs, a renin receptor, ANG-converting enzyme-2, ANG (<em>1</em>-<em>7</em>), the function of the ANG type 2 receptor, and ANG receptor heterodimerization. The role of the RAS in the regulation of cardiovascular and renal function is reviewed and discussed in light of these newly recognized components.

<em>Angiotensin</em> II (AngII) helps to regulate overall renal tubular reabsorption of salt and water, yet its effects in the distal nephron have not been well studied. The purpose of these studies was to determine whether AngII stimulates luminal Na(+) transport in the cortical collecting duct (CCD). Intracellular Na(+) concentration ([Na(+)](i)), as a reflection of Na(+) transport across the apical membrane, was measured with fluorescence microscopy using sodium-binding benzofuran isophthalate (SBFI) in isolated, perfused CCD segments dissected from rabbit kidneys. Control [Na(+)](i), during perfusion with 25 mM NaCl and a Na(+)-free solution in the bath containing the Na(+)-ionophore monensin (<em>1</em>0 microM, to eliminate basolateral membrane Na(+) transport) averaged <em>1</em>9.3 +/- 5.2 mM (n = <em>1</em>6). Increasing luminal [NaCl] to <em>1</em>50 mM elevated [Na(+)](i) by 9.8<em>7</em> +/- <em>1</em>.5 mM (n = <em>7</em>; P < 0.05). AngII (<em>1</em>0(-9) M) added to the lumen significantly elevated baseline [Na(+)](i) by 6.3 +/- <em>1</em>.0 mM and increased the magnitude (Delta = 25.2 +/- 3.<em>7</em> mM) and initial rate ( approximately 5 fold) of change in [Na(+)](i) to increased luminal [NaCl]. AngII when added to the bath had similar stimulatory effects; however, AngII was much more effective from the lumen. Thus, AngII significantly increased the apical entry of Na(+) in the CCD. To determine if this apical entry step occurred via the epithelial Na(+) channel (ENaC), studies were performed using the specific ENaC blocker, benzamil hydrochloride (<em>1</em>0(-6) M). When added to the perfusate, benzamil almost completely inhibited the elevations in [Na(+)](i) to increased luminal [NaCl] in both the presence and absence of AngII. These results suggest that AngII directly stimulates Na(+) channel activity in the CCD. AT(<em>1</em>) receptor blockade with candesartan or losartan (<em>1</em>0(-6) M) prevented the stimulatory effects of AngII. Regulation of ENaC activity by AngII may play an important role in distal Na(+) reabsorption in health and disease.

The incidence and prevalence of diabetes mellitus have grown significantly throughout the world, due primarily to the increase in type 2 diabetes. This overall increase in the number of people with diabetes has had a major impact on development of diabetic kidney disease (DKD), one of the most frequent complications of both types of diabetes. DKD is the leading cause of end-stage renal disease (ESRD), accounting for approximately 50% of cases in the developed world. Although incidence rates for ESRD attributable to DKD have recently stabilized, these rates continue to rise in high-risk groups such as middle-aged African Americans, Native Americans, and Hispanics. The costs of care for people with DKD are extraordinarily high. In the Medicare population alone, DKD-related expenditures among this mostly older group were nearly $25 billion in 20<em>1</em><em>1</em>. Due to the high human and societal costs, the Consensus Conference on Chronic Kidney Disease and Diabetes was convened by the American Diabetes Association in collaboration with the American Society of Nephrology and the National Kidney Foundation to appraise issues regarding patient management, highlighting current practices and new directions. Major topic areas in DKD included <em>1</em>) identification and monitoring, 2) cardiovascular disease and management of dyslipidemia, 3) hypertension and use of renin-<em>angiotensin</em>-aldosterone system blockade and mineralocorticoid receptor blockade, 4) glycemia measurement, hypoglycemia, and drug therapies, 5) nutrition and general care in advanced-stage chronic kidney disease, 6) children and adolescents, and <em>7</em>) multidisciplinary approaches and medical home models for health care delivery. This current state summary and research recommendations are designed to guide advances in care and the generation of new knowledge that will meaningfully improve life for people with DKD.