Nitroglycerin
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Publication
Journal: The Journal of clinical investigation
June/13/1996
Abstract
We tested the hypothesis that angiotensin II-induced hypertension is associated with an increase in vascular .O2- production, and characterized the oxidase involved in this process. Infusion of angiotensin II (0.7 mg/kg per d) increased systolic blood pressure and doubled vascular .O2- production (assessed by lucigenin chemiluminescence), predominantly from the vascular media. NE infusion (2.75 mg/kg per d) produced a similar degree of hypertension, but did not increase vascular .O2- production. Studies using various enzyme inhibitors and vascular homogenates suggested that the predominant source of .O2- activated by angiotensin II infusion is an NADH/NADPH-dependent, membrane-bound oxidase. Angiotensin II-, but not NE-, induced hypertension was associated with impaired relaxations to acetylcholine, the calcium ionophore A23187, and nitroglycerin. These relaxations were variably corrected by treatment of vessels with liposome-encapsulated superoxide dismutase. When Losartan was administered concomitantly with angiotensin II, vascular .O2- production and relaxations were normalized, demonstrating a role for the angiotensin type-1 receptor in these processes. We conclude that forms of hypertension associated with elevated circulating levels of angiotensin II may have unique vascular effects not shared by other forms of hypertension because they increase vascular smooth muscle .O2- production via NADH/NADPH oxidase activation.
Publication
Journal: Circulation
May/11/2000
Abstract
BACKGROUND
Endothelial vasodilator dysfunction is a characteristic feature of patients at risk for coronary atherosclerosis. Therefore, we prospectively investigated whether coronary endothelial dysfunction predicts disease progression and cardiovascular event rates.
RESULTS
Coronary vasoreactivity was assessed in 147 patients using the endothelium-dependent dilator acetylcholine, sympathetic activation by cold pressor testing, dilator responses to increased blood flow, and dilation in response to nitroglycerin. Cardiovascular events (cardiovascular death, unstable angina, myocardial infarction, percutaneous transluminal coronary angioplasty, coronary bypass grafting, ischemic stroke, or peripheral artery revascularization) served as outcome variables over a median follow-up period of 7.7 years. Patients suffering from cardiovascular events during follow-up (n=16) had significantly increased vasoconstrictor responses to acetylcholine infusion (P=0. 009) and cold pressor testing (P=0.002), as well as significantly blunted vasodilator responses to increased blood flow (P<0.001) and the intracoronary injection of nitroglycerin (P=0.001). Impaired endothelial and endothelium-independent coronary vasoreactivity were associated with a significantly higher incidence of cardiovascular events by Kaplan-Meier analysis. By multivariate analysis, all tests of coronary vasoreactivity were significant, independent predictors of a poor prognosis, even after adjustment for traditional cardiovascular risk factors or the presence of atherosclerosis itself.
CONCLUSIONS
Coronary endothelial vasodilator dysfunction predicts long-term atherosclerotic disease progression and cardiovascular event rates. Thus, the assessment of coronary endothelial vasoreactivity can provide pivotal information as both a diagnostic and prognostic tool in patients at risk for coronary heart disease.
Publication
Journal: Nature
September/13/1993
Abstract
Congeners of nitrogen monoxide (NO) are neuroprotective and neurodestructive. To address this apparent paradox, we considered the effects on neurons of compounds characterized by alternative redox states of NO: nitric oxide (NO.) and nitrosonium ion (NO+). Nitric oxide, generated from NO. donors or synthesized endogenously after NMDA (N-methyl-D-aspartate) receptor activation, can lead to neurotoxicity. Here, we report that NO.- mediated neurotoxicity is engendered, at least in part, by reaction with superoxide anion (O2.-), apparently leading to formation of peroxynitrite (ONOO-), and not by NO. alone. In contrast, the neuroprotective effects of NO result from downregulation of NMDA-receptor activity by reaction with thiol group(s) of the receptor's redox modulatory site. This reaction is not mediated by NO. itself, but occurs under conditions supporting S-nitrosylation of NMDA receptor thiol (reaction or transfer of NO+). Moreover, the redox versatility of NO allows for its interconversion from neuroprotective to neurotoxic species by a change in the ambient redox milieu. The details of this complex redox chemistry of NO may provide a mechanism for harnessing neuroprotective effects and avoiding neurotoxicity in the central nervous system.
Publication
Journal: The New England journal of medicine
November/12/1986
Abstract
Acetylcholine is believed to dilate normal blood vessels by promoting the release of a vasorelaxant substance from the endothelium (endothelium-derived relaxing factor). By contrast, if the endothelium is removed experimentally, acetylcholine constricts blood vessels. We tested the hypothesis that muscarinic cholinergic vasodilation is impaired in coronary atherosclerosis. Graded concentrations of acetylcholine and, for comparison, the nonendothelial-dependent vasodilator nitroglycerin were infused into the left anterior descending artery of eight patients with advanced coronary stenoses (greater than 50 percent narrowing), four subjects with angiographically normal coronary arteries, and six patients with mild coronary atherosclerosis (less than 20 percent narrowing). Vascular responses were evaluated by quantitative angiography. In several segments each of four normal coronary arteries, acetylcholine caused a dose-dependent dilation from a control diameter of 1.94 +/- 0.16 mm to 2.16 +/- 0.15 mm with the maximal acetylcholine dose (P less than 0.01). In contrast, all eight of the arteries with advanced stenoses showed dose-dependent constriction, from 1.05 +/- 0.05 to 0.32 +/- 0.16 mm at the highest concentration of acetylcholine (P less than 0.01), with temporary occlusion in five. Five of six vessels with minimal disease also constricted in response to acetylcholine. All vessels dilated in response to nitroglycerin, however. We conclude that paradoxical vasoconstriction induced by acetylcholine occurs early as well as late in the course of coronary atherosclerosis. Our preliminary findings suggest that the abnormal vascular response to acetylcholine may represent a defect in endothelial vasodilator function, and may be important in the pathogenesis of coronary vasospasm.
Publication
Journal: Journal of the American College of Cardiology
December/4/1995
Abstract
OBJECTIVE
The relation between endothelium-dependent vasodilator function in the brachial and coronary arteries was determined in the same subjects.
BACKGROUND
Coronary artery endothelial dysfunction precedes the development of overt atherosclerosis and is important in its pathogenesis. A noninvasive assessment of endothelial function in a peripheral conduit vessel, the brachial artery, was recently described, but the relation between brachial artery function and coronary artery vasodilator function has not been explored.
METHODS
In 50 patients referred to the catheterization laboratory for the evaluation of coronary artery disease (mean age +/- SD 56 +/- 10 years), the coronary vasomotor response to serial intracoronary infusions of the endothelium-dependent agonist acetylcholine (10(-8) to 10(-6) mol/liter), was studied. Endothelium-dependent vasodilation was also assessed in the brachial artery by measuring the change in brachial artery diameter in response to reactive hyperemia.
RESULTS
Patients with coronary artery endothelial dysfunction manifested as vasoconstriction in response to acetylcholine had significantly impaired flow-mediated vasodilation in the brachial artery compared with that of patients with normal coronary endothelial function (4.8 +/- 5.5% vs. 10.8 +/- 7.6%, p < 0.01). Patients with coronary artery disease also had an attenuated brachial artery vasodilator response compared with that of patients with angiographically smooth coronary arteries (4.5 +/- 4.6% vs. 9.7 +/- 8.1%, p < 0.02). By multivariate analysis, the strongest predictors of reduced brachial dilator responses to flow were baseline brachial artery diameter (p < 0.001), coronary endothelial dysfunction (p = 0.003), the presence of coronary artery disease (p = 0.007) and cigarette smoking (p = 0.016). The brachial artery vasodilator response to sublingual nitroglycerin was independent of coronary endothelial responses or the presence of coronary artery disease. The positive predictive value of abnormal brachial dilation ( < 3%) in predicting coronary endothelial dysfunction is 95%.
CONCLUSIONS
This study demonstrated a close relation between coronary artery endothelium-dependent vasomotor responses to acetylcholine and flow-mediated vasodilation in the brachial artery. This noninvasive method may become a useful surrogate in assessing the predisposition to atherosclerosis in patients with cardiac risk factors.
Publication
Journal: The Journal of pharmacology and experimental therapeutics
April/24/1985
Abstract
Hemoglobin at 1 microM reduced and at 10 microM abolished the endothelium-dependent relaxation induced by acetylcholine or by A23187 in rabbit aortic rings. Similarly, methylene blue at 10 microM reduced and at 50 microM abolished relaxation induced by acetylcholine and by A23187. Furthermore, hemoglobin (1-10 microM) and methylene blue (10-50 microM) each induced a dose-dependent inhibition of the endothelium-independent relaxation produced by glyceryl trinitrate, but neither had any effect on the relaxation produced by isoproterenol. The inhibitory effects of hemoglobin and methylene blue may be due to blockade of guanylate cyclase, as the rises in cyclic GMP content which accompany relaxation induced by acetylcholine, A23187 or glyceryl trinitrate were abolished. Isoproterenol-induced relaxation took place with no change in cyclic GMP content. Hemoglobin and methylene blue appear therefore to inhibit selectively vaso-relaxation induced by agents which increase cyclic GMP levels. Hemoglobin and methylene blue augment tone in aortic rings, particularly when endothelial cells are present, suggesting that the endothelium-derived relaxing factor (EDRF) might be released spontaneously in low concentrations. The possibility that hemoglobin inhibits endothelium-dependent and glyceryl trinitrate-induced relaxation by binding EDRF and nitric oxide, respectively, is discussed together with the proposal that methylene blue might produce its effects by oxidizing a component of guanylate cyclase, possibly a ferrous heme group linked to the enzyme molecule. Methylene blue might, in addition, interact directly with EDRF.
Publication
Journal: Proceedings of the National Academy of Sciences of the United States of America
June/8/1989
Abstract
The role of endothelium-derived nitric oxide in the regulation of blood pressure in the anesthetized rabbit was studied with N omega-monomethyl-L-arginine (L-NMMA), a specific inhibitor of its formation from L-arginine. L-NMMA (3-100 mg.kg-1), but not its D-enantiomer, induced a dose-dependent long-lasting (15-90 min) increase in mean systemic arterial blood pressure. L-NMMA (100 mg.kg-1) also inhibited significantly the hypotensive action of acetylcholine, without affecting that of glyceryl trinitrate. Both these actions of L-NMMA were reversed by L-arginine (300 mg.kg-1), but not by D-arginine (300 mg.kg-1), indomethacin (1 mg.kg-1), prazosin (0.3 mg.kg-1), or by vagotomy. The effects of L-NMMA in vivo were associated with a significant inhibition of the release of nitric oxide from perfused aortic segments ex vivo. This inhibition was reversed by infusing L-arginine through the aortic segments. These results indicate that nitric oxide formation from L-arginine by the vascular endothelium plays a role in the regulation of blood pressure and in the hypotensive actions of acetylcholine.
Publication
Journal: Lancet (London, England)
December/4/1989
Abstract
NG monomethyl-L-arginine (L-NMMA), a specific inhibitor of the synthesis of endothelium-derived nitric oxide (NO), was infused into the brachial arteries of healthy volunteers to study the role of NO in the control of forearm blood flow. L-NMMA caused a 50% fall in basal blood flow and attenuated the dilator response to infused acetylcholine but not that to glyceryl trinitrate. These results indicate that the dilator action of endothelium-derived NO contributes to the control of basal and stimulated regional blood flow in man. Impairment of production of NO might account for the abnormalities in vascular reactivity that characterise a wide variety of disease states.
Publication
Journal: American heart journal
May/1/1973
Publication
Journal: Journal of the American College of Cardiology
August/15/1994
Abstract
OBJECTIVE
This study assessed whether aging is associated with progressive endothelial dysfunction, whether the pattern of any age-related decline in vascular health is different in men and women and whether any gender difference is consistent with known changes in hormonal status.
BACKGROUND
Coronary and cerebrovascular disease are much less common in young and middle-aged women compared with men, although the gender difference in death from atherosclerosis is less marked after the menopause. Endothelial dysfunction is an early event in atherogenesis and is important in dynamic plaque stenosis in later life. The effect of aging on endothelial function in men and women, however, is not well known.
METHODS
We used high resolution ultrasound to study endothelium-dependent and endothelium-independent vascular responses. Brachial artery physiology was investigated in 238 subjects (103 men, 135 women; mean [+/- SD] age 38 +/- 17 years, range 15 to 72) with no known risk factors for atherosclerosis. The responses to reactive hyperemia (flow-mediated dilation, which is endothelium dependent) and to glyceryl trinitrate (an endothelium-independent dilator) were assessed for all the subjects and then for men and women separately.
RESULTS
On multivariate analysis for the whole group, reduced flow-mediated dilation was related to older age (r = -0.34, p < 0.0001). In men, flow-mediated dilation was preserved in subjects aged < or = 40 years but declined thereafter at 0.21%/year. In women, flow-mediated dilation was stable until the early 50s, after which it declined at 0.49%/year (p = 0.002 compared with men). In contrast, there was no significant change in the glyceryl trinitrate response with aging in either gender.
CONCLUSIONS
Aging is associated with progressive endothelial dysfunction in normal humans, and this appears to occur earlier in men than in women. In women, however, a steep decline commences at around the time of the menopause. This is consistent with a protective effect of estrogens on the arterial wall.
Publication
Journal: Journal of the American College of Cardiology
August/24/1997
Abstract
OBJECTIVE
This study assessed the clinical utility of mitral annulus velocity in the evaluation of left ventricular diastolic function.
BACKGROUND
Mitral inflow velocity recorded by Doppler echocardiography has been widely used to evaluate left ventricular diastolic function but is affected by other factors. The mitral annulus velocity profile during diastole may provide additional information about left ventricular diastolic function.
METHODS
Mitral annulus velocity during diastole was measured by Doppler tissue imaging (DTI) 1) in 59 normal volunteers (group 1); 2) in 20 patients with a relaxation abnormality as assessed by Doppler mitral inflow variables (group 2) at baseline and after saline loading; 3) in 11 patients (group 3) with normal diastolic function before and after intravenous nitroglycerin infusion; and 4) in 38 consecutive patients (group 4) undergoing cardiac catheterization in whom mitral inflow velocity and tau as well as mitral annulus velocity were measured simultaneously.
RESULTS
In group 1, mean +/- SD peak early and late diastolic mitral annulus velocity was 10.0 +/- 1.3 and 9.5 +/- 1.5 cm/s, respectively. In group 2, mitral inflow velocity profile changed toward the pseudonormalization pattern with saline loading (deceleration time 311 +/- 84 ms before to 216 +/- 40 ms after intervention, p < 0.001), whereas peak early diastolic mitral annulus velocity did not change significantly (5.3 +/- 1.2 cm/s to 5.7 +/- 1.4 cm/s, p = NS). In group 3, despite a significant change in mitral inflow velocity profile after nitroglycerin, peak early diastolic mitral annulus velocity did not change significantly (9.5 +/- 2.2 cm/s to 9.2 +/- 1.7 cm/s, p = NS). In group 4, peak early diastolic mitral annulus velocity (r = -0.56, p < 0.01) and the early/late ratio (r = -0.46, p < 0.01) correlated with tau. When the combination of normal mitral inflow variables with prolonged tau (> or = 50 ms) was classified as pseudonormalization, peak early diastolic mitral annulus velocity < 8.5 cm/s and the early/late ratio < 1 could identify the pseudonormalization with a sensitivity of 88% and specificity of 67%.
CONCLUSIONS
Mitral annulus velocity determined by DTI is a relatively preload-independent variable in evaluating diastolic function.
Publication
Journal: Science (New York, N.Y.)
September/24/2008
Abstract
There is substantial interest in the development of drugs that limit the extent of ischemia-induced cardiac damage caused by myocardial infarction or by certain surgical procedures. Here, using an unbiased proteomic search, we identified mitochondrial aldehyde dehydrogenase 2 (ALDH2) as an enzyme whose activation correlates with reduced ischemic heart damage in rodent models. A high-throughput screen yielded a small-molecule activator of ALDH2 (Alda-1) that, when administered to rats before an ischemic event, reduced infarct size by 60%, most likely through its inhibitory effect on the formation of cytotoxic aldehydes. In vitro, Alda-1 was a particularly effective activator of ALDH2*2, an inactive mutant form of the enzyme that is found in 40% of East Asian populations. Thus, pharmacologic enhancement of ALDH2 activity may be useful for patients with wild-type or mutant ALDH2 who are subjected to cardiac ischemia, such as during coronary bypass surgery.
Publication
Journal: Journal of cardiology
December/14/1992
Abstract
Five patients with typical myocardial stunning were presented. They had chest pain and had electrocardiographic abnormalities matching the symptoms of acute myocardial infarction (AMI) but had no coronary artery stenoses on angiogram (CAG). The prevalence of cases with these clinical manifestations was 1.2% among 415 consecutive AMI patients who were examined invasively. The electrocardiographic abnormalities varied; ST elevations were observed in 4 patients, R waves decreased transiently in one, and Q waves developed in one patient. Typical left ventriculogram (LVG) was akinesis in the apical, diaphragmatic and/or anterolateral segments, but hyperkinesis in the basal segments. This akinesis was transient and resolved in 7 days. CAG revealed diffuse multi-vessel spasms in 2 patients, which were also observed in additional 2 patients after ergonovine administration. The intracoronary administration of nitroglycerin disclosed no coronary artery stenoses in any of the patients.
Publication
Journal: The New England journal of medicine
March/5/2007
Abstract
Systemic inflammation may impair vascular function, and epidemiologic data suggest a possible link between periodontitis and cardiovascular disease.
We randomly assigned 120 patients with severe periodontitis to community-based periodontal care (59 patients) or intensive periodontal treatment (61). Endothelial function, as assessed by measurement of the diameter of the brachial artery during flow (flow-mediated dilatation), and inflammatory biomarkers and markers of coagulation and endothelial activation were evaluated before treatment and 1, 7, 30, 60, and 180 days after treatment.
Twenty-four hours after treatment, flow-mediated dilatation was significantly lower in the intensive-treatment group than in the control-treatment group (absolute difference, 1.4%; 95% confidence interval [CI], 0.5 to 2.3; P=0.002), and levels of C-reactive protein, interleukin-6, and the endothelial-activation markers soluble E-selectin and von Willebrand factor were significantly higher (P<0.05 for all comparisons). However, flow-mediated dilatation was greater and the plasma levels of soluble E-selectin were lower in the intensive-treatment group than in the control-treatment group 60 days after therapy (absolute difference in flow-mediated dilatation, 0.9%; 95% CI, 0.1 to 1.7; P=0.02) and 180 days after therapy (difference, 2.0%; 95% CI, 1.2 to 2.8; P<0.001). The degree of improvement was associated with improvement in measures of periodontal disease (r=0.29 by Spearman rank correlation, P=0.003). There were no serious adverse effects in either of the two groups, and no cardiovascular events occurred.
Intensive periodontal treatment resulted in acute, short-term systemic inflammation and endothelial dysfunction. However, 6 months after therapy, the benefits in oral health were associated with improvement in endothelial function.
Publication
Journal: Circulation
December/2/1993
Abstract
BACKGROUND
Cigarette smoking is the most important modifiable risk factor for atherosclerosis. Endothelial dysfunction is an early event in atherogenesis, and we hypothesized that smoking might be associated with endothelial damage in the systemic arteries of otherwise healthy young adults.
RESULTS
We studied noninvasively the brachial arteries of 200 subjects aged 15 to 57 years, all normotensive, nondiabetic with cholesterol level < or = 240 mg/dL and no family history of premature vascular disease: 80 control subjects aged 16 to 56 years (mean, 35), 80 current smokers aged 15 to 55 years (mean, 33), and 40 former smokers aged 25 to 57 years (mean, 38). Total lifetime amount smoked varied from 1 to 75 pack years in the smokers. Using high-resolution ultrasound, vessel diameter was measured at rest, during reactive hyperemia (with flow increase causing endothelium-dependent dilation), and after sublingual glyceryl trinitrate (GTN, an endothelium-independent vasodilator). Flow-mediated dilation (FMD) was observed in all the control subjects (10 +/- 3.3%; range, 4% to 22%) but was impaired or absent in the smokers (4 +/- 3.9%; range, 0% to 17%; P < .0001). FMD in the smokers was inversely related to lifetime dose smoked (6.6 +/- 4.0% in very light smokers, 4.0 +/- 3.1% in light smokers, 3.2 +/- 3.2% in moderate smokers, and 2.6 +/- 1.2% in heavy smokers; P < .01). FMD for the former smokers was 5.1 +/- 4.1% (range, 0% to 15%). In a multivariate model adjusting for age, sex, cholesterol, smoking history, and vessel size, former smoking was associated with a higher FMD than current smoking (P = .07); when only male former and current smokers were considered, the higher FMD was significant (P = .0001) but not for female smokers (P = .24). GTN caused dilation in all subjects (control subjects, 20 +/- 5.2%; smokers, 17 +/- 5.8%; former smokers, 17.4 +/- 5.4%). Vessel diameter, baseline flow, and degree of reactive hyperemia (Doppler estimated) were similar in all groups.
CONCLUSIONS
Cigarette smoking is associated with dose-related and potentially reversible impairment of endothelium-dependent arterial dilation in asymptomatic young adults, consistent with endothelial dysfunction.
Publication
Journal: JAMA
April/3/2002
Abstract
BACKGROUND
Decompensated congestive heart failure (CHF) is the leading hospital discharge diagnosis in patients older than 65 years.
OBJECTIVE
To compare the efficacy and safety of intravenous nesiritide, intravenous nitroglycerin, and placebo.
METHODS
Randomized, double-blind trial of 489 inpatients with dyspnea at rest from decompensated CHF, including 246 who received pulmonary artery catheterization, that was conducted at 55 community and academic hospitals between October 1999 and July 2000.
METHODS
Intravenous nesiritide (n = 204), intravenous nitroglycerin (n = 143), or placebo (n = 142) added to standard medications for 3 hours, followed by nesiritide (n = 278) or nitroglycerin (n = 216) added to standard medication for 24 hours.
METHODS
Change in pulmonary capillary wedge pressure (PCWP) among catheterized patients and patient self-evaluation of dyspnea at 3 hours after initiation of study drug among all patients. Secondary outcomes included comparisons of hemodynamic and clinical effects between nesiritide and nitroglycerin at 24 hours.
RESULTS
At 3 hours, the mean (SD) decrease in PCWP from baseline was -5.8 (6.5) mm Hg for nesiritide (vs placebo, P<.001; vs nitroglycerin, P =.03), -3.8 (5.3) mm Hg for nitroglycerin (vs placebo, P =.09), and -2 (4.2) mm Hg for placebo. At 3 hours, nesiritide resulted in improvement in dyspnea compared with placebo (P =.03), but there was no significant difference in dyspnea or global clinical status with nesiritide compared with nitroglycerin. At 24 hours, the reduction in PCWP was greater in the nesiritide group (-8.2 mm Hg) than the nitroglycerin group (-6.3 mm Hg), but patients reported no significant differences in dyspnea and only modest improvement in global clinical status.
CONCLUSIONS
When added to standard care in patients hospitalized with acutely decompensated CHF, nesiritide improves hemodynamic function and some self-reported symptoms more effectively than intravenous nitroglycerin or placebo.
Publication
Journal: Analytical chemistry
March/19/2007
Abstract
A new ion source has been developed for rapid, noncontact analysis of materials at ambient pressure and at ground potential. The new source, termed DART (for "Direct Analysis in Real Time"), is based on the reactions of electronic or vibronic excited-state species with reagent molecules and polar or nonpolar analytes. DART has been installed on a high-resolution time-of-flight mass spectrometer (TOFMS) that provides improved selectivity and accurate elemental composition assignment through exact mass measurements. Although DART has been applied to the analysis of gases, liquids, and solids, a unique application is the direct detection of chemicals on surfaces without requiring sample preparation, such as wiping or solvent extraction. DART has demonstrated success in sampling hundreds of chemicals, including chemical agents and their signatures, pharmaceutics, metabolites, peptides and oligosaccharides, synthetic organics, organometallics, drugs of abuse, explosives, and toxic industrial chemicals. These species were detected on various surfaces, such as concrete, asphalt, human skin, currency, airline boarding passes, business cards, fruits, vegetables, spices, beverages, body fluids, horticultural leaves, cocktail glasses, and clothing. DART employs no radioactive components and is more versatile than devices using radioisotope-based ionization. Because its response is instantaneous, DART provides real-time information, a critical requirement for screening or high throughput.
Publication
Journal: Hypertension (Dallas, Tex. : 1979)
October/31/2001
Abstract
Pressure wave reflection in the upper limb causes amplification of the arterial pulse so that radial systolic and pulse pressures are greater than in the ascending aorta. Wave transmission properties in the upper limbs (in contrast to the descending aorta and lower limbs) change little with age, disease, and drug therapy in adult humans. Such consistency has led to use of a generalized transfer function to synthesize the ascending aortic pressure pulse from the radial pulse. Validity of this approach was tested for estimation of aortic systolic, diastolic, pulse, and mean pressures from the radial pressure waveform. Ascending aortic and radial pressure waveforms were recorded simultaneously at cardiac surgery, before initiation of cardiopulmonary bypass, with matched, fluid-filled manometer systems in 62 patients under control conditions and during nitroglycerin infusion. Aortic pressure pulse waves, generated from the radial pulse, showed agreement with the measured aortic pulse waves with respect to systolic, diastolic, pulse, and mean pressures, with mean differences <1 mm Hg. Control differences in Bland-Altman plots for mean+/-SD in mm Hg were systolic, 0.0+/-4.4; diastolic, 0.6+/-1.7; pulse, -0.7+/-4.2; and mean pressure, -0.5+/-2.0. For nitroglycerin infusion, differences respectively were systolic, -0.2+/-4.3; diastolic, 0.6+/-1.7; pulse, -0.8+/-4.1; and mean pressure, -0.4+/-1.8. Differences were within specified limits of the Association for the Advancement of Medical Instrumentation SP10 criteria. In contrast, differences between recorded radial and aortic systolic and pulse pressures were well outside the criteria (respectively, 15.7+/-8.4 and 16.3+/-8.5 for control and 14.5+/-7.3 and 15.1+/-7.3 mm Hg for nitroglycerin). Use of a generalized transfer function to synthesize radial artery pressure waveforms can provide substantially equivalent values of aortic systolic, pulse, mean, and diastolic pressures.
Publication
Journal: Circulation
May/12/1997
Abstract
BACKGROUND
Central aortic pressures and waveform convey important information about cardiovascular status, but direct measurements are invasive. Peripheral pressures can be measured noninvasively, and although they often differ substantially from central pressures, they may be mathematically transformed to approximate the latter. We tested this approach, examining intersubject and intrasubject variability and the validity of using a single averaged transformation, which would enhance its applicability.
RESULTS
Invasive central aortic pressure by micromanometer and radial pressure by automated tonometry were measured in 20 patients at steady state and during hemodynamic transients (Valsalva maneuver, abdominal compression, nitroglycerin, or vena caval obstruction). For each patient, transfer functions (TFs) between aortic and radial pressures were calculated by parametric model and results averaged to yield individual TFs. A generalized TF was the average of individual functions. TFs varied among patients, with coefficients of variation for peak amplitude and frequency at peak amplitude of 24.9% and 16.9%, respectively. Intrapatient TF variance with altered loading (> 20% variation in peak amplitude) was observed in 28.5% of patients. Despite this, the generalized TF estimated central arterial pressures to < or = 0.2 +/- 3.8 mm Hg error, arterial compliance to 6 +/- 7% accuracy, and augmentation index to within -7% points (30 +/- 45% accuracy). Individual TFs were only marginally superior to the generalized TF for reconstructing central pressures.
CONCLUSIONS
Central aortic pressures can be accurately estimated from radial tonometry with the use of a generalized TF. The reconstructed waveform can provide arterial compliance estimates but may underestimate the augmentation index because the latter requires greater fidelity reproduction of the wave contour.
Publication
Journal: American journal of physiology. Endocrinology and metabolism
December/15/2004
Abstract
GLP-1 stimulates insulin secretion, suppresses glucagon secretion, delays gastric emptying, and inhibits small bowel motility, all actions contributing to the anti-diabetogenic peptide effect. Endothelial dysfunction is strongly associated with insulin resistance and type 2 diabetes mellitus and may cause the angiopathy typifying this debilitating disease. Therefore, interventions affecting both endothelial dysfunction and insulin resistance may prove useful in improving survival in type 2 diabetes patients. We investigated GLP-1's effect on endothelial function and insulin sensitivity (S(I)) in two groups: 1) 12 type 2 diabetes patients with stable coronary artery disease and 2) 10 healthy subjects with normal endothelial function and S(I). Subjects underwent infusion of recombinant GLP-1 or saline in a random crossover study. Endothelial function was measured by postischemic FMD of brachial artery, using ultrasonography. S(I) [in (10(-4) dl.kg(-1).min(-1))/(muU/ml)] was measured by hyperinsulinemic isoglycemic clamp technique. In type 2 diabetic subjects, GLP-1 infusion significantly increased relative changes in brachial artery diameter from baseline FMD(%) (3.1 +/- 0.6 vs. 6.6 +/- 1.0%, P < 0.05), with no significant effects on S(I) (4.5 +/- 0.8 vs. 5.2 +/- 0.9, P = NS). In healthy subjects, GLP-1 infusion affected neither FMD(%) (11.9 +/- 0.9 vs. 10.3 +/- 1.0%, P = NS) nor S(I) (14.8 +/- 1.8 vs. 11.6 +/- 2.0, P = NS). We conclude that GLP-1 improves endothelial dysfunction but not insulin resistance in type 2 diabetic patients with coronary heart disease. This beneficial vascular effect of GLP-1 adds yet another salutary property of the peptide useful in diabetes treatment.
Publication
Journal: Circulation
May/20/2001
Abstract
BACKGROUND
Altered endothelial cell nitric oxide (NO(*)) production in atherosclerosis may be due to a reduction of intracellular tetrahydrobiopterin, which is a critical cofactor for NO synthase (NOS). In addition, previous literature suggests that inactivation of NO(*) by increased vascular production superoxide (O(2)(*-)) also reduces NO(*) bioactivity in several disease states. We sought to determine whether these 2 seemingly disparate mechanisms were related.
RESULTS
Endothelium-dependent vasodilation was abnormal in aortas of apoE-deficient (apoE(-/-)) mice, whereas vascular superoxide production (assessed by 5 micromol/L lucigenin) was markedly increased. Treatment with either liposome-entrapped superoxide dismutase or sepiapterin, a precursor to tetrahydrobiopterin, improved endothelium-dependent vasodilation in aortas from apoE(-/-) mice. Hydrogen peroxide had no effect on the decay of tetrahydrobiopterin, as monitored spectrophotometrically. In contrast, superoxide modestly and peroxynitrite strikingly increased the decay of tetrahydrobiopterin over 500 seconds. Luminol chemiluminescence, inhibitable by the peroxynitrite scavengers ebselen and uric acid, was markedly increased in apoE(-/-) aortic rings. In vessels from apoE(-/-) mice, uric acid improved endothelium-dependent relaxation while having no effect in vessels from control mice. Treatment of normal aortas with exogenous peroxynitrite dramatically increased vascular O(2)(*-) production, seemingly from eNOS, because this effect was absent in vessels lacking endothelium, was blocked by NOS inhibition, and did not occur in vessels from mice lacking eNOS.
CONCLUSIONS
Reactive oxygen species may alter endothelium-dependent vascular relaxation not only by the interaction of O(2)(*-) with NO(*) but also through interactions between peroxynitrite and tetrahydrobiopterin. Peroxynitrite oxidation of tetrahydrobiopterin may represent a pathogenic cause of "uncoupling" of NO synthase.
Publication
Journal: Lancet (London, England)
August/18/1998
Abstract
BACKGROUND
Cluster headache, one of the most severe pain syndromes in human beings, is usually described as a vascular headache. However, the striking circadian rhythmicity of this strictly half-sided pain syndrome cannot be readily explained by the vascular hypothesis. We aimed to assess changes in regional cerebral blood flow (rCBF) in patients with cluster headache.
METHODS
We used positron emission tomography (PET) to assess the changes in rCBF, as an index of synaptic activity, during nitroglycerin-induced cluster headache attacks in nine patients who had chronic cluster headache. Eight patients who had cluster headache but were not in the bout acted as a control group.
RESULTS
In the acute pain state, activation was seen in the ipsilateral inferior hypothalamic grey matter, the contralateral ventroposterior thalamus, the anterior cingulate cortex, and bilaterally in the insulae. Activation in the hypothalamus was seen solely in the pain state and was not seen in patients who have cluster headache but were out of the bout.
CONCLUSIONS
Our findings establish central nervous system dysfunction in the region of the hypothalamus as the primum movens in the pathophysiology of cluster headache. We suggest that a radical reappraisal of this type of headache is needed and that it should in general terms, be regarded as a neurovascular headache, to give equal weight to the pathological and physiological mechanisms that are at work.
Publication
Journal: Journal of physiology and pharmacology : an official journal of the Polish Physiological Society
June/19/2003
Abstract
In retrospect, basic research in the fields of NO and cyclic GMP during the past two decades appears to have followed a logical course beginning with the findings that NO and cyclic GMP are vascular smooth muscle relaxants, that nitroglycerin relaxes smooth muscle by metabolism to NO, progressing to the discovery that mammalian cells synthesize NO, and finally the revelation that NO is a neurotransmitter mediating vasodilation in specialized vascular beds. A great deal of basic and clinical research on the physiological and pathophysiological roles of NO in cardiovascular function has been conducted since the discovery that EDRF is NO. The new knowledge on NO should enable investigators in this field to develop novel and more effective therapeutic strategies for the prevention, diagnosis and treatment of numerous cardiovascular disorders. Since NO elicits a protective and beneficial action in many disease states, novel NO donor drugs for clinical use should prove to be very effective drugs for the treatment of essential hypertension, stroke, coronary artery disease, vascular complications of diabetes, impotency and other disorders involving the vascular system.
Publication
Journal: Lancet (London, England)
June/9/1994
Abstract
GISSI-3 is a multicentre randomised clinical trial to assess the efficacy of lisinopril, transdermal glyceryl trinitrate (GTN), and their combination in improving survival and ventricular function after acute myocardial infarction (AMI). Between June, 1991, and July, 1993, 19,394 patients were randomised from 200 coronary care units in Italy. Eligible patients presented within 24 h of symptom onset and had no clear indications for or against the study treatments. In a factorial design patients were randomly assigned 6 weeks of oral lisinopril (5 mg initial dose and then 10 mg daily) or open control as well as nitrates (intravenous for the first 24 h followed by transdermal GTN 10 mg daily) or open control. Complete clinical data and 6-week follow-up were available for 18,895 (97.4%) patients randomised. Two-dimensional echocardiographic data were available for 14,209 patients. Overall 6-week mortality was 6.7%. Lisinopril, started within 24 h from AMI symptoms, produced significant reductions in overall mortality (odds ratio 0.88 [95% CI 0.79-0.99]) and in the combined outcome measure of mortality and severe ventricular dysfunction (0.90 [0.84-0.98]). In the same trial the systematic administration of transdermal GTN did not show any independent effect on the same outcome measures (0.94 [0.84-1.05] and 0.94 [0.87-1.02]). Systematic combined administration of lisinopril and GTN also produced significant reductions in overall mortality (0.83 [0.70-0.97]) and in the combined endpoint (0.85 [0.76-0.94]). The favourable effect of lisinopril alone or with GTN was clear also in the predefined high-risk populations (elderly patients and women) for the combined endpoint. These findings were obtained in a population intensively exposed to recommended treatments (thrombolysis 72%, beta-blockade 31%, and aspirin 84%); non-protocol treatment with angiotensin-converting-enzyme inhibitors and nitrates was allowed for specific clinical indications. No excess of unfavourable clinically relevant events in the treated groups was reported.
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