Voltage-gated L-type (Cav1.2 and Cav1.3) channels are widely expressed in cardiovascular tissues and represent the critical drug-target for the treatment of several cardiovascular diseases. The two isoforms are also abundantly expressed in neuronal and neuroendocrine tissues. In the brain, Cav1.2 and Cav1.3 channels control synaptic plasticity, somatic activity, neuronal differentiation and brain aging. In neuroendocrine cells, they are involved in the genesis of action potential generation, bursting activity and hormone secretion. Recent studies have shown that Cav1.2 and Cav1.3 are also expressed in chromaffin cells but their functional role has not yet been identified despite that L-type channels possess interesting characteristics, which confer them an important role in the control of catecholamine secretion during action potentials stimulation. In intact rat adrenal glands L-type channels are responsible for adrenaline and noradrenaline release following splanchnic nerve stimulation or nicotinic receptor activation. L-type channels can be either up- or down-modulated by membrane autoreceptors following distinct second messenger pathways. L-type channels are tightly coupled to BK channels and activate at relatively low-voltages. In this way they contribute to the action potential hyperpolarization and to the pace-maker current controlling action potential firings. L-type channels are shown also to regulate the fast secretion of the immediate readily releasable pool of vesicles with the same Ca(2+)-efficiency of other voltage-gated Ca(2+) channels. In mouse adrenal slices, repeated action potential-like stimulations drive L-type channels to a state of enhanced stimulus-secretion efficiency regulated by beta-adrenergic receptors. Here we will review all these novel findings and discuss the possible implication for a specific role of L-type channels in the control of chromaffin cells activity.

OBJECTIVE

A proportion of preterm, very low birthweight (VLBW, < 1500 g) infants may show inadequate adrenal response to stress in the immediate postnatal period. The human corticotrophin releasing hormone (hCRH) stimulation test was used to: (a) determine the relation between pituitary-adrenal response and systemic blood pressure in these infants; (b) characterise the endocrinological features of transient adrenocortical insufficiency of prematurity (TAP).

METHODS

A total of 226 hCRH tests were performed on 137 VLBW infants on day 7 and 14 of life in a tertiary neonatal centre.

RESULTS

Basal, peak, and incremental rise in serum cortisol (Delta Cort(0-30)) on day 7 were associated significantly with the lowest systolic, mean, and diastolic blood pressures recorded during the first two weeks of life (r>> 0.25, p < 0.005). These cortisol concentrations also correlated significantly but negatively with the maximum and total cumulative dose of dopamine (r>> -0.22, p < 0.02), dobutamine (r>> -0.18, p < 0.04), and adrenaline (r>> -0.26, p < 0.004), total volume of crystalloid (r>> -0.22, p < 0.02), and duration of inotrope treatment (r>> -0.25, p < 0.006). Multivariate regression analysis of significant factors showed that the lowest systolic, mean, and diastolic blood pressures remained independently associated with serum cortisol (basal, peak, and Delta Cort(0-30)) on day 7. Hypotensive infants requiring inotropes (group 2) were significantly less mature and more sick than infants with normal blood pressure (group 1). The areas under the ACTH response curves were significantly greater in group 2 than in group 1, on both day 7 (p = 0.004) and day 14 (p = 0.004). In contrast, the area under the cortisol response curve was significantly greater in group 1 than in group 2 on day 7 (p = 0.001), but there was no significant difference between the two groups on day 14. In addition, serum cortisol at the 50th centile in hypotensive infants had high specificity and positive predictive value (0.80-0.93 and 0.81-0.89 respectively) for predicting early neonatal hypotension.

CONCLUSIONS

This study characterises the fundamental endocrinological features of TAP: normal or exaggerated pituitary response; adrenocortical insufficiency; good recovery of adrenal function by day 14 of postnatal life. The results also provide the centiles of serum cortisol for hypotensive patients and infants with normal blood pressure, and show a significant relation between serum cortisol and blood pressure in VLBW infants.

We looked at the relation between systemic arterial blood pressure and recovery from spinal cord injury by inducing both hypertension and hypotension in 25 rats randomly allocated to five equal groups. The rats received no injury, a mild (2.3-g), or a severe (53.0-g) spinal cord injury lasting 1 minute. We used the hydrogen clearance technique to measure spinal cord blood flow at the injury site (T1) and at an adjacent site (C6). Mean systemic arterial blood pressure was either increased with adrenaline or decreased by phlebotomy in 20-mm-Hg intervals except for the severe-injury group, in which the posttraumatic pressure could only be increased with adrenaline. Spinal cord blood flow remained constant in the no-injury group between 81 and 180 mm Hg. After a mild injury, induced moderate hypertension (121-140 mm Hg) improved spinal cord blood flow significantly, whereas hypotension decreased it in a linear fashion. Severe injury caused a marked decrease in spinal cord blood flow and mean systemic arterial blood pressure. Even extreme hypertension (161-180 mm Hg) induced by adrenaline did not significantly increase spinal cord blood flow at T1 but caused hyperemia at C6 due to loss of autoregulation. In conclusion, normotension should be attempted, irrespective of the severity of spinal cord injury. Induced hypertension after severe spinal cord injury was not beneficial in improving spinal cord blood flow at the injury site while potentially increasing hemorrhage and edema.

The vascular grafts prepared by electrospinning often have relatively small pores, which limit cell infiltration into the grafts and hinder the regeneration and remodeling of the grafts into neoarteries. To overcome this problem, macroporous electrospun polycaprolactone (PCL) scaffolds with thicker fibers (5-6 μm) and larger pores (∼30 μm) were fabricated in the present study. In vitro cell culture indicated that macrophages cultured on thicker-fiber scaffolds tended to polarize into the immunomodulatory and tissue remodeling (M2) phenotype, while those cultured on thinner-fiber scaffolds expressed proinflammatory (M1) phenotype. In vivo implantation by replacing rat abdominal aorta was performed and followed up for 7, 14, 28 and 100 d. The results demonstrated that the macroporous grafts markedly enhanced cell infiltration and extracellular matrix (ECM) secretion. All grafts showed satisfactory patency for up to 100 days. At day 100, the endothelium coverage was complete, and the regenerated smooth muscle layer was correctly organized with abundant ECM similar to those in the native arteries. More importantly, the regenerated arteries demonstrated contractile response to adrenaline and acetylcholine-induced relaxation. Analysis of the cellularization process revealed that the thicker-fiber scaffolds induced a large number of M2 macrophages to infiltrate into the graft wall. These macrophages further promoted cellular infiltration and vascularization. In conclusion, the present study confirmed that the scaffold structure can regulate macrophage phenotype. Our thicker-fiber electrospun PCL vascular grafts could enhance the vascular regeneration and remodeling process by mediating macrophage polarization into M2 phenotype, suggesting that our constructs may be a promising cell-free vascular graft candidate and are worthy for further in vivo evaluation.

During acute systemic infectious disease, precisely regulated release of energy-rich substrates (glucose, free fatty acids, and amino acids) and auxiliary elements such as calcium/phosphorus from storage sites (fat tissue, muscle, liver, and bone) are highly important because these factors are needed by an energy-consuming immune system in a situation with little or no food/water intake (sickness behavior). This positively selected program for short-lived infectious diseases is similarly applied during chronic inflammatory diseases. This review presents the interaction of hormones and inflammation by focusing on energy storage/expenditure and volume regulation. Energy storage hormones are represented by insulin (glucose/lipid storage and growth-related processes), insulin-like growth factor-1 (IGF-1) (muscle and bone growth), androgens (muscle and bone growth), vitamin D (bone growth), and osteocalcin (bone growth, support of insulin, and testosterone). Energy expenditure hormones are represented by cortisol (breakdown of liver glycogen/adipose tissue triglycerides/muscle protein, and gluconeogenesis; water retention), noradrenaline/adrenaline (breakdown of liver glycogen/adipose tissue triglycerides, and gluconeogenesis; water retention), growth hormone (glucogenic, lipolytic; has also growth-related aspects; water retention), thyroid gland hormones (increase metabolic effects of adrenaline/noradrenaline), and angiotensin II (induce insulin resistance and retain water). In chronic inflammatory diseases, a preponderance of energy expenditure pathways is switched on, leading to typical hormonal changes such as insulin/IGF-1 resistance, hypoandrogenemia, hypovitaminosis D, mild hypercortisolemia, and increased activity of the sympathetic nervous system and the renin-angiotensin-aldosterone system. Though necessary during acute inflammation in the context of systemic infection or trauma, these long-standing changes contribute to increased mortality in chronic inflammatory diseases.

OBJECTIVE

IV line insertion and drugs did not affect long-term survival in an out-of-hospital cardiac arrest (OHCA) randomized clinical trial (RCT). In a previous large registry study adrenaline was negatively associated with survival from OHCA. The present post hoc analysis on the RCT data compares outcomes for patients actually receiving adrenaline to those not receiving adrenaline.

METHODS

Patients from a RCT performed May 2003 to April 2008 were included. Three patients from the original intention-to-treat analysis were excluded due to insufficient documentation of adrenaline administration. Quality of cardiopulmonary resuscitation (CPR) and clinical outcomes were compared.

RESULTS

Clinical characteristics were similar and CPR quality comparable and within guideline recommendations for 367 patients receiving adrenaline and 481 patients not receiving adrenaline. Odds ratio (OR) for being admitted to hospital, being discharged from hospital and surviving with favourable neurological outcome for the adrenaline vs. no-adrenaline group was 2.5 (CI 1.9, 3.4), 0.5 (CI 0.3, 0.8) and 0.4 (CI 0.2, 0.7), respectively. Ventricular fibrillation, response interval, witnessed arrest, gender, age and endotracheal intubation were confounders in multivariate logistic regression analysis. OR for survival for adrenaline vs. no-adrenaline adjusted for confounders was 0.52 (95% CI: 0.29, 0.92).

CONCLUSIONS

Receiving adrenaline was associated with improved short-term survival, but decreased survival to hospital discharge and survival with favourable neurological outcome after OHCA. This post hoc survival analysis is in contrast to the previous intention-to-treat analysis of the same data, but agrees with previous non-randomized registry data. This shows limitations of non-randomized or non-intention-to-treat analyses.

1 Pieces of rabbit jejunum were bathed in Krebs solution at 37 degrees C in an isolated organ bath bubbled with O2 and 5% CO2. The bathing fluid was collected regularly and assayed for prostaglandins. 2 The preparations maintained a continuous sub-maximal muscle contraction, referred to as inherent 'tone'. Prostaglandins E2 and F2alpha were continuously generated by the intestine and released into the bathing fluid. The amounts released first declined over 2 h and then steadily increased. The release was also greater after 48 h storage in the refrigerator and after mechanical damage. 3 There was no change in prostaglandin release when the rabbit jejunum was contractd by acetylcholine or physostigmine or relaxed by adrenaline, hyoscine, papaverine, dinitrophenol, or calcium-free Krebs solution. 4 Addition to the bathing fluid of the prostaglandin precursor, arachidonic acid, did not increase the release of prostaglandins although it contracted the tissue. Thus, output of prostaglandins from the tissue was not limited by substrate concentration but more probably by the capacity of the prostaglandin synthetase. 5 Prostaglandin output was decreased by bubbling the bathing fluid with N2 rather than O2; at the same time the preparation relaxed. 6 Aspirin-like drugs such as indomethacin also decreased or abolished prostaglandin formation and this, too, was accompanied by loss of tone of the isolated preparation. 7 Pieces of rabbit jejunum stored in Krebs solution containing indomethacin initially released little or no prostaglandin into the bathing fluid. However, prostaglandin release increased with repeated washing of the preparation. 8 The results suggest that intra-mural prostaglandin production contributes to the inherent tone of the rabbit jejunum, that trauma increases prostaglandin production and that the inhibitory effects of anoxia are linked with the lack of prostaglandin production and activity. The relevance of these findings to intestinal activity in vivo is discussed.

Severe hypoglycaemia with cognitive dysfunction is 3 times more common in intensively, rather than conventionally, treated insulin-dependent diabetes mellitus (IDDM). To investigate the effect of diabetes control on higher brain function during acute hypoglycaemia, we studied one of the earliest detectable changes in cognitive function, i.e. the four-choice reaction time, and symptomatic and hormonal responses during euglycaemic and hypoglycaemic clamping in human subjects. There were no changes in symptoms or counterregulatory hormones and four-choice reaction time was stable during 220 min of euglycaemic insulin clamping in five men with IDDM, with a coefficient of variation of less than 2.2% (1% for accuracy) for the cognitive function test. During stepped hypoglycaemic clamping however, hormonal responses and subjective awareness of hypoglycaemia occurred in all groups but started at much lower blood glucose concentrations in eight intensively-treated diabetic subjects (Group 1) than in ten conventionally-treated (Group 2) or in eight non-diabetic subjects (Group 3). For example, for adrenaline, plasma glucose thresholds were 2.7 +/- 0.2 vs 3.4 +/- 0.2 and 3.2 +/- 0.1 mmol/l, respectively, p < 0.05, Group 1 vs Groups 2 or 3 and for subjective awareness of hypoglycaemia 2.3 +/- 0.2 vs 3.0 +/- 0.1 and 3.2 +/- 0.1 mmol/l, p < or = 0.003), as in previous studies. In contrast, deterioration in reaction time occurred at 3.2 +/- 0.3, 3.2 +/- 0.2 and 3.0 +/- 0.2 mmol/l, respectively (p = NS), thus occurring at higher glucose levels than subjective awareness in the intensively-treated subjects only. The altered hierarchy of responses to hypoglycaemia in well-controlled intensively-treated diabetes explains the increased risk of severe hypoglycaemia without warning seen in such patients.

BACKGROUND

Therapeutic endoscopy has provided a new means of treating bleeding peptic ulcers. Additional medical therapy may enhance the therapeutic benefit. Hemostasis is highly pH dependent and is severely impaired at low pH. Proton pump inhibitors, by achieving a significantly higher inhibition of gastric acidity, may improve the therapeutic outcomes after endoscopic treatment of ulcers.

METHODS

We enrolled 166 patients with hemorrhage from duodenal, gastric, or stomal ulcers and signs of recent hemorrhage, as confirmed by endoscopy. Twenty-six patients had ulcers with an arterial spurt, 41 patients had active ooze, 37 had a visible vessel, and 62 patients had an adherent clot. All patients received endoscopic injection sclerotherapy using 1:10,000 adrenaline and 1% polidocanol and were randomly assigned to receive omeprazole (40 mg orally) every 12 hours for 5 days or an identical-looking placebo. The outcome measures used were recurrent bleeding, surgery, blood transfusion, and hospital stay.

RESULTS

Six (7%) of 82 patients in the omeprazole group had recurrent bleeding, as compared with 18 (21%) in the placebo group (P = 0.02). Two patients in the omeprazole group and 7 patients in the placebo group needed surgery to control their bleeding (P = 0.17). One patient in the omeprazole group and 2 patients in the placebo group died (P = 0.98). Twenty-nine patients (35%) in the omeprazole group and 61 patients (73%) in the placebo group received blood transfusions (P <0.001). The average hospital stay was 4.6 +/- 1.1 days in the omeprazole group and 6.0 +/- 0.7 days in the placebo group (P <0.001).

CONCLUSIONS

The addition of oral omeprazole to combination injection sclerotherapy decreases the rate of recurrent bleeding, reduces the need for surgery and transfusion, and shortens the hospital stay for patients with stigmata of recent hemorrhage.

The adrenaline-forming enzyme (phenylethanolamine N-methyltransferase) was elevated in the A1 and A2 regions of the brainstem of 4-week-old spontaneously (genetic) hypertensive rats and in the A1 region of adult experimentally (deoxycorticosterone acetate and sodium chloride) hypertensive rats. The administration of a phenylethanolamine N-methyltransferase inhibitor to experimentally hypertensive animals caused a reduction of the elevated blood pressure to normal values. These results implicate adrenaline-containing neurons in the brainstem in the development of hypertension.

OBJECTIVE

Dexmedetomidine, an alpha(2)-adrenoceptor agonist, exhibits anti-nociceptive actions at the spinal cord and enhances the effect of local anaesthetics in the peripheral nervous system. Although the latter action may be attributed in part to inhibition of nerve conduction produced by dexmedetomidine, this has not been fully examined yet.

METHODS

We examined the effects of various adrenoceptor agonists including dexmedetomidine, and tetracaine, a local anaesthetic, on compound action potentials (CAPs) recorded from the frog sciatic nerve, using the air-gap method.

RESULTS

Dexmedetomidine reversibly and concentration-dependently reduced the peak amplitude of CAPs (IC(50)= 0.40 mmol x L(-1)). This action was not antagonized by two alpha(2)-adrenoceptor antagonists, yohimbine and atipamezole; the latter antagonist itself reduced CAP peak amplitude. Clonidine and oxymetazoline, two other alpha(2)-adrenoceptor agonists, also inhibited CAPs; the maximum effect of clonidine was only 20%, while oxymetazoline was less potent (IC(50)= 1.5 mmol x L(-1)) than dexmedetomidine. On the other hand, (+/-)-adrenaline, (+/-)-noradrenaline, alpha(1)-adrenoceptor agonist (-)-phenylephrine and beta-adrenoceptor agonist (-)-isoprenaline (each 1 mmol x L(-1)) had no effect on CAPs. Tetracaine reversibly reduced CAP peak amplitude (IC(50) of 0.014 mmol x L(-1)).

CONCLUSIONS

Dexmedetomidine reduced CAP peak amplitude without alpha(2)-adrenoceptor activation (at concentrations >1000-fold higher than those used as alpha(2) adrenoceptor agonist), with a lower potency than tetracaine. CAPs were inhibited by other alpha(2) adrenoceptor agonists, oxymetazoline and clonidine, and also an alpha(2) adrenoceptor antagonist atipamezole. Thus, some drugs acting on alpha(2) adrenoceptors are able to block nerve conduction.

Neurons projecting from the rostral ventrolateral medulla (RVL) to the spinal cord were antidromically identified in rats anesthetized with urethane, paralyzed, and ventilated. The sites of lowest antidromic threshold were concentrated in the intermediolateral nucleus (IML). Their axonal conduction velocities were distributed bimodally, with the mean of the rapidly conducting fibers (greater than 1 m/sec) being 3.1 +/- 0.1 m/sec (n = 105), and of the slower axons being 0.8 +/- 0.03 m/sec (n = 25). Single-shock electrical stimulation of RVL elicited 2 bursts of excitation in splanchnic sympathetic nerve activity (SNA), which resulted from activation of 2 descending pathways with conduction velocities comparable to those of antidromically excited RVL-spinal neurons. The probability of discharge of RVL-spinal cells was synchronized both with the cardiac-related bursts in SNA with functional baroreceptor reflexes and with the free-running 2-6 Hz bursts in SNA following baroreceptor afferent denervation. On the average, their spontaneous discharges occurred 67 +/- 2 msec (n = 31) prior to the peak of the spontaneous bursts in splanchnic SNA. This time corresponded to the latency to the peak of the early excitatory potential in splanchnic SNA following electrical stimulation of RVL. Baroreceptor reflex activation inhibited RVL-spinal neurons. The recording sites of RVL-spinal vasomotor neurons were consistently located within 100 micron of cell bodies (C1 neurons) immunoreactive for the adrenaline-synthesizing enzyme phenylethanolamine N-methyltransferase (PNMT). Ultrastructural analysis of the lateral funiculus of the cervical and thoracic spinal cord demonstrated PNMT immunoreactivity within myelinated (0.6-2.1 micron diameter) and unmyelinated (0.1-0.8 micron diameter) axons. Estimated conduction velocities of these fibers were comparable to the antidromic conduction velocities of the rapidly and slowly conducting populations of RVL-spinal vasomotor neurons. We conclude that in rat, the discharge of RVL-spinal vasomotor neurons strongly influences SNA: the baroreceptor-mediated inhibition of these neurons is reflected in the cardiac locking of SNA, while, in the absence of baroreceptor input, the synchronous discharge of RVL-spinal neurons maintains a free-running 2-6 Hz bursting pattern in SNA. RVL-spinal neurons are located within, and may be elements of, the C1 adrenergic cell group, and they provide a sympathoexcitatory drive to neurons in the IML over rapidly and slowly conducting pathways that correspond to myelinated and unmyelinated spinal axons containing PNMT.

Effects of adrenaline on the smooth muscle of the rabbit common carotid artery were studied by the partitional chamber method. The experiments on excitation-contraction coupling were carried out in isotonic Krebs solution; the other experiments were carried out in hypertonic Krebs solution. Adrenaline (10(-7) g/ml) caused rhythmical electrical and mechanical activity of arterial strips in isotonic Krebs solution. By addition of adrenaline (10(-5) g/ml), the membrane was depolarized by about 10 mv and the amplitude of the electrotonic potential was decreased by 40-50% of the control in hypertonic Krebs solution. Present experimental results suggest that the depolarization of the membrane and the decrease of the amplitude of the electrotonic potential in the artery are due to the increase of Na and Cl conductance. Contraction appeared in all preparations exposed to 10(-8) g/ml adrenaline; at that concentration membrane potential and membrane resistance showed little or no change.

1. The administration of glucagon to fed rats by intraperitoneal injection, or the perfusion of livers from fed rats with glucagon by the method of Mortimore [Mortimore (1963) Am.J. Physiol. 204, 699--704] was associated with increases of 15- and 5-fold respectively, in the time for which a given load of exogenous Ca2+ is retained by mitochondria subsequently isolated from the liver. This effect of glucagon was (a) also induced by N6O2'-dibutyryl cyclic AMP, (b) completely blocked by cycloheximide, (c) relatively slow in onset (15--60 min) and (d) associated with a stimulation of about 20% in the rates of ADP-stimulated oxygen utilization and Ca2+ transport measured in the presence of succinate. 2. Perfusion of livers with glucagon resulted in the isolation of mitochandria which showed a 50% increase, no significant change and a 40% increase in the concentrations of endogenous Ca, Mg and Pi respectively, when compared with mitochondria isolated from control perfused livers. 3. The administration of insulin or adrenaline to fed rats induced increases of 10- and 8-fold respectively, in the time for which Ca2+ is retained by isolated liver mitochondria. Perfusion of livers with insulin had no effect on mitochondrial Ca2+ retention time. 4. The perfusion of livers from starved rats with glucagon, or the administration of either glucagon or insulin to starved rats, increased by about 2.5- and 15-fold respectively, the time for which isolated mitochondria retain Ca2+. 5. Mechanisms which may be responsible for the observed alterations in Ca2+-retention time are discussed.

Panic disorder can serve as a clinical model for testing whether mental stress can cause heart disease. Potential neural mechanisms of cardiac risk are the sympathetic activation during panic attacks, continuing release of adrenaline as a co-transmitter in the cardiac sympathetic nerves, and impairment of noradrenaline neuronal reuptake, augmenting sympathetic neural respnses. The phenotype of impaired neuronal reuptake of noradrenaline: an epigenetic mechanism? We suspect that this phenotype, in sensitizing people to heart symptom development, is a cause of panic disorder, and by magnifying the sympathetic neural signal in the heart, underlies increased cardiac risk. No loss of function mutations of the coding region of the norepinephrine transporter (NET) are evident, but we do detect hypermethylation of CpG islands in the NET gene promoter region. Chromatin immunoprecipitation methodology demonstrates binding of the inhibitory transcription factor, MeCP2, to promoter region DNA in panic disorder patients. Cardiovascular illnesses co-morbid with panic disorder. Panic disorder commonly coexists with essential hypertension and the postural tachycardia syndrome. In both of these cardiovascular disorders the impaired neuronal noradrenaline reuptake phenotype is also present and, as with panic disorder, is associated with NET gene promoter region DNA hypermethylation. An epigenetic 'co-morbidity' perhaps underlies the clinical concordance. Brain neurotransmitters. Using internal jugular venous sampling, in the absence of a panic attack we find normal norepinephrine turnover, but based on measurements of the overflow of the serotonin metabolite, 5HIAA, a marked increase (six to sevenfold) in brain serotonin turnover in patients with panic disorder. This appears to represent the underlying neurotransmitter substrate for the disorder. Whether this brain serotonergic activation is a prime mover, or consequential on other primary causes of panic disorder, including cardiac sensitization by faulty neuronal noradrenaline reuptake leading to cardiac symptoms and the enhanced vigilance which accompanies them, is unclear at present.

Circulating platelet aggregates formed in vivo were serially measured, and platelet-aggregation thresholds were determined in vitro in 82 patients with acute cerebral ischaemia. The percentage of aggregated platelets was increased in 53 patients with completed stroke (30.9% +/- 2.0) and in 29 patients with transient ischaemic attacks (34.1% +/- 2.3), all studied within 10 days of the acute event. These values were higher (P less than 0.001) than levels of aggregated platelets in 30 patients with non-vascular neurological disease (16.8% +/- 2.3). The percentage of aggregated platelets returned to normal 10 days to 6 wk after acute cerebral ischaemia. Aspirin and dipyridamole did not affect either the increase in or subsequent normalisation of circulating-platelet-aggregate levels in these patients. Platelet-aggregation sensitivity to adenosine diphosphate and adrenaline was also increased in patients with acute cerebral ischaemia, but this abnormally resolved during convalescence. Platelet activation is abnormal in acute cerebral ischaemia but usually returns to normal with or without anti-platelet therapy. This activation of platelets may contribute to the clinical manifestations of occlusive vascular disease.

A method is described for the quantification of vascular smooth muscle cell growth from individual explants of contractile rabbit aortic tunica media. The precision of the method probably depends on regular explant geometry (1-mm squares) and pooling sufficient explants. Serum-induced growth was quantified by measurements of ATP concentration, incorporation of [3H]thymidine and DNA concentration. The possible effects of endogenous vasodilator agents on growth were investigated by using lipid soluble analogues of their second messengers, namely 8-Br-cAMP and 8-Br-cGMP, which are known to relax rabbit aortic strips. Cell growth was inhibited concentration-dependently by 8-Br-cAMP but not 8-Br-cGMP (0.01-1 mM). The effect of 8-Br-cAMP was reversible, and also occurred when addition was delayed until after growth had commenced. The results imply that endogenous vasodilators such as prostacyclin, adenosine and adrenaline, which increase cAMP concentration, may normally suppress smooth muscle cell growth, whereas nitric oxide and atriopeptins, which increase cGMP concentration, may not.

Various cardiovascular effects of a new synthetic coronary vasodilator, alpha-isopropyl-alpha [(N-methyl - N - homoveratryl)-gamma-amino-propyl]-3, 4-dimethoxyphenylacetonitrile HCI (D365, Iproveratril or Isoptin) have been studied. In isolated perfused rabbit hearts the drug exerts a potent coronary vasodilator action, but can depress myocardial contractions and A-V conduction. In anesthetized cats it produces varying degrees of hypotension with bradycardia, and antagonizes ST-T changes induced by ouabain. It can also protect against chloroform-adrenaline and ouabain ventricular fibrillation. On isolated papillary muscle preparations it can lead to adrenergic blockade. It is concluded that in addition to its coronary dilator action, the drug exerts ;quinidine-like' antiarrythmic effects, and appears to deserve further study.

The effects of p-chloromercuribenzoic acid and chloromercuribenzene-p-sulphonic acid on pancreatic islets were studied in vitro. Obese-hyperglycaemic mice were used as the source of microdissected islets containing more than 90% beta-cells. p-Chloromercuribenzoic acid and chloromercuribenzene-p-sulphonic acid stimulated insulin release at concentrations of 0.01mm or above. This stimulation was significantly inhibited by the omission of Ca(2+) or the addition of adrenaline, diazoxide or 2,4-dinitrophenol. p-Chloromercuribenzoic acid or chloromercuribenzene-p-sulphonic acid did not interfere with the insulin-releasing ability of glucose. Micro-perifusion experiments revealed that the release of insulin in response to organic mercurial occurred almost instantaneously, was reversible, and was biphasic. The two mercurials inhibited glucose transport as well as glucose oxidation, and increased the mannitol and sucrose spaces of isolated islets. Compared with the effects on insulin release, those on glucose transport and membrane permeability were characterized by a longer latency and/or required higher concentrations of organic mercurial. Apart from a seemingly higher proportion of beta-cells exhibiting certain degenerative features, in islets exposed to 0.1mm-chloromercuribenzene-p-sulphonic acid for 60min, no significant differences with respect to beta-cell fine structure were noted between non-incubated islets and islets incubated with chloromercuribenzene-p-sulphonic acid or glucose or both. It is suggested that insulin release may be regulated by relatively superficial thiol groups in the beta-cell plasma membrane.

The effect of the noradrenaline neurotoxin DSP4 on the postnatal development of central noradrenergic neurons in the rat has been investigated using neurochemical techniques. The results demonstrated a preferential effect of DSP4 on the locus coeruleus noradrenergic neuron system without any notable effects on the dopamine and adrenaline neurons and only a minor neurotoxic effect on the serotonin neurons. The effect of DSP4 on the serotonin neurons could be completely prevented by pretreatment with the uptake blocker zimelidine, without affecting the action of DSP4 on noradrenergic neurons. Neonatal DSP4 treatment systemically led to permanent depletions of noradrenaline in the cerebral cortex and spinal cord and marked increases of noradrenaline in the cerebellum and pons-medulla. These effects of DSP4 were dose-dependent and could be blocked by pretreatment with the noradrenaline uptake blocker desipramine. The alterations in endogenous noradrenaline levels were quantitatively similar to changes observed in [3H]noradrenaline uptake in slices in vitro. There were no significant changes of these noradrenergic parameters when analysing the whole CNS after neonatal DSP4 treatment, in spite of marked regional changes in both directions. Administration of DSP4 to rats of different ages produced acutely marked depletions of noradrenaline in all regions including the pons-medulla and the cerebellum at all developmental stages. Marked and permanent depletions of noradrenaline were found in the distant noradrenergic nerve terminal projections after treatment at all ages, whereas increases in noradrenaline levels in the pons-medulla and cerebellum were only observed in rats treated with DSP4 up to the age of 3-5 days, whereas a DSP4 administration in older rats led to substantial and permanent depletions of noradrenaline in both these regions. The results indicate that the alteration of the postnatal development of noradrenergic neurons after treatment of rats up to the age of 3-5 days is mainly related to a 'pruning effect' of DSP4, in which prevention of the development of distant nerve terminal projections causes an increased outgrowth of nerves in collateral systems spared by the neurotoxin. The results indicate that DSP4 may be a useful denervation tool for studying various aspects of noradrenergic neurotransmission of developing locus coeruleus neurons.

On the basis of histochemical and pharmacological studies, catecholamines have been implicated in central mechanisms controlling respiration. This hypothesis was tested in iontophoretic studies on neurones located in bulbar respiratory centres. Adrenaline and noradrenaline had a predominantly depressant effect on respiratory as well as on closely situated non-respiratory units. These depressions were mimicked by the application of isoproterenol and clonidine; acetylcholine and serotonin had inconsistent effects on these neurones. In control experiments, microinjections, using a Hamilton syringe, were made in the area of bulbar respiratory centres: noradrenaline, but not serotonin, depressed the central respiratory activity reflected in the phrenic nerve discharge. These results suggest that specific adrenergic and noradrenergic depressant mechanisms could affect both respiratory and other physiological centres at the bulbar level.

In participants of a comprehensive residential three month yoga and mediation training programme living on a low fat lacto-vegetarian diet changes in cardiovascular risk factors and hormones were studied. Substantial risk factor reduction was found. Body mass index, total serum and LDL cholesterol, fibrinogen, and blood pressure were significantly reduced especially in those with elevated levels. Urinary excretion of adrenaline, noradrenaline, dopamine, aldosterone, as well as serum testosterone and luteinizing hormone levels were reduced, while cortisol excretion increased significantly.

Preparations of the cranial segment of the rat inferior vena cava preincubated with 3H-noradrenaline were superfused in the presence of desipramine and corticosterone. Tritium overflow was stimulated electrically (2 Hz). The experiments were carried out in spirally cut strips with or without intima or in segments ligated at both ends and superfused either on the adventitial side ("conventionally") or "inside out". In spirally cut strips electrically evoked 3H overflow was increased by isoprenaline and procaterol, but much less so by prenalterol. Adrenaline 1 nmol/l increased overflow, but at high concentrations it reduced it, just as noradrenaline did at all concentrations. The concentration-response curve for isoprenaline was shifted to the right by propranolol (apparent pA2:8.29) and even more so by ICI 118-551, whereas atenolol was less potent (apparent pA2:6.42). Rauwolscine which, given alone, increased the evoked 3H overflow antagonized the inhibitory effect of noradrenaline (apparent pA2:7.58). These findings indicate that beta 2- and alpha 2-adrenoceptors mediating facilitation and inhibition of noradrenaline release, respectively, are present in the vena cava. The response to isoprenaline (at all concentrations) was considerably lower in segments superfused "conventionally" than in spirally cut strips, but no difference was observed with respect to the effects of noradrenaline, rauwolscine and angiotensin II. The effect of isoprenaline was clearly more pronounced in segments superfused "inside out" than in segments superfused "conventionally". In spirally cut strips angiotensin II increased 3H overflow. This effect was antagonized by saralasin, suggesting the involvement of facilitatory angiotensin receptors. In spirally cut strips or segments superfused "inside out", saralasin or captopril considerably attenuated the facilitatory effect of isoprenaline on 3H overflow. Conversely, in the presence of isoprenaline, captopril inhibited the electrically evoked 3H overflow in spirally cut strips, whereas in the absence of isoprenaline, captopril was ineffective. In conclusion, angiotensin receptors and alpha 2-adrenoceptors appear to be located on the sympathetic nerve endings, but a major part of the beta 2-adrenoceptors probably is subendothelial (most likely on smooth muscle cells). Angiotensin II, synthesized in response to beta 2-adrenoceptor activation, probably stimulates angiotensin receptors on the noradrenergic nerves, leading to an increase in noradrenaline release.

Platelets from Galphaq knockout mice are unable to aggregate in response to physiological agonists like adenosine 5'-diphosphate (ADP), thromboxane A(2), thrombin, or collagen, although shape change still occurs in response to all of these agonists except ADP. ADP-induced platelet aggregation results from simultaneous activation of the purinergic P2Y(1) receptor coupled to calcium mobilization and shape change and of a distinct P2 receptor, P2cyc, coupled through Gi to adenylyl cyclase inhibition, which is responsible for completion and amplification of the response. P2cyc could be the molecular target of the antithrombotic drug clopidogrel and the adenosine triphosphate (ATP) analogs AR-C69931MX, AR-C67085, and AR-C66096. The aim of the present study was to determine whether externally added ADP could still act through the Gi pathway in Galphaq-deficient mouse platelets and thereby amplify the residual responses to agonists such as thrombin or collagen. It was found that (1) ADP and adrenaline still inhibited cyclic AMP accumulation in Galphaq-deficient platelets; (2) both agonists restored collagen- but not thrombin-induced aggregation in these platelets; (3) the effects of ADP were selectively inhibited in vitro by the ATP analog AR-C69931MX and ex vivo by clopidogrel and hence were apparently mediated by the P2cyc receptor; and (4) high concentrations of ADP (100 micromol/L) induced aggregation without shape change in Galphaq-deficient platelets through activation of P2cyc. Since adrenaline was not able to induce platelet aggregation even at high concentrations, we conclude that the effects of ADP mediated by P2cyc are not restricted to the inhibition of adenylyl cyclase through Gi(2).