Search results for "serpin"
showing 10 items of 76 documents
Effects of beta-adrenoceptor drug stimulation on various models of gastric ulcer in rats.
1982
Abstract 1. Experiments were designed to evaluate the effect of the pharmacological activation of beta-adrenoceptors on various models of gastric ulcer in the rat. 2. Pretreatment with the beta-adrenoceptor stimulant drugs, isoprenaline or salbutamol, significantly inhibited stress-induced gastric ulcers. This anti-ulcer effect was abolished by propranolol but not by atenolol, suggesting that beta 2-adrenoceptors mediate this response. 3. In the pylorus-ligation model, salbutamol inhibited lesion formation and reduced the intragastric content of hydrogen ions, histamine and pepsin although the latter was only affected with the higher dose of salbutamol. 4. Salbutamol also prevented the ulce…
The specificity of prostaglandin E2 (PGE2) in reducing coronary vascular resistance: A comparison with adenosine.
1978
Experiments were performed on the isolated, electrically driven guinea-pig heart, perfused at constant rate. All animals were pretreated with reserpine. Myocardial contractile force (MCF), coronary perfusion pressure (CPP) and myocardial oxygen consumption (QO2) were monitored continuously. Both adenosine (ADO) and PGE2 produced a concentration-dependent decrease in the CPP. The ED50 (50% of maximum response) was 2.1 +/- 0.6 X 10(-9)M for PGE2 but 40 +/- 7 X 10(-9)M for ADO (P less than 0.01) at 1.8 mM Ca(e). This coronary vasodilation was independent of the external Ca-concentration, which was varied between 0.55-9.0 mM. PGE2 had no effect on MCF or QO2 and the effect of ADO was only sligh…
Drug induced variations of the renin-angiotensin-aldosterone system in rats. II. Antihypertensives
1977
Summary Groups of male rats were treated with antihypertensive drugs (alpha-methyl-dopa, clonidine, propranolol, reserpine, diazoxide) which were administered under conditions causing the onset of high plasma renin activity (PRA) and high plasma and urine aldosterone levels, i.e. together with distilled water load (5% of body weight). Alpha-methyl-dopa and propranolol, which fail to significantly alter PRA and plasma aldosterone levels when administered without distilled water load, cause a marked decrease of plasma and urine aldosterone levels and of PRA when administered together with distilled water load, while diazoxide, and reserpine cause a marked increase of these values. Clonidine c…
Light and drug induced changes of epiphysial synaptic ribbons.
1976
In the present investigation experiments were carried out to determine whether the functionally obscure synaptic rebbons of mammalian pinealocytes can be affected by acute changes in environmental lighting and which chemical processes may be involved in their regulation. Experiments carried out in male guinea-pigs have shown that the amounts of synaptic ribbons are immediately affected by changes in the lighting pattern. Extension of the light period reduced the normally occurring increase, whereas extension of the dark period inhibited the normally occurring decrease in the amount of synaptic ribbons. Results following injections of a number of drugs known to influence pineal function (nor…
The role of choline in the release of acetylcholine in isolated hearts.
1978
1. The concentrations of acetylcholine, choline and noradrenaline were estimated in the perfusate (overflow) of isolated hearts of chickens, cats, rabbits and guinea pigs. Neurotransmitter release was evoked by stimulation of both vagus nerves and by direct stimulation of the heart (field stimulation). 2. In the absence of exogenous choline and physostigmine, field stimulation at 20 Hz for 20 min caused an overflow of acetylcholine from the hearts of the 4 species investigated. During vagal stimulation, however, acetylcholine was detected only in the perfusate of the chicken heart. 3. Field stimulation for 2 min caused an overflow of 193 pmol g−1 min−1 acetylcholine and of 666 pmol g−1 min−…
The inhibition by dopamine of cholinergic transmission in the isolated guinea-pig ileum. Mediation through alpha-adrenoceptors.
1982
1. Segments of the guinea-pig ileum were incubated in Tyrode's solution containing 3 μM propranolol. Dopamine, like noradrenaline and clonidine, inhibited the twitch response to field stimulation. The inhibitory action of dopamine remained unchanged in the presence of the dopamine uptake inhibitor nomifensine (1 μM). Tissue from reserpine-pretreated amimals was insensitive to tyramine but the response to dopamine was not affected. It is, therefore, assumed that the effect of dopamine is due to a direct receptor stimulation and not to the release of noradrenaline. 2. The inhibitory action of dopamine was not antagonized by the dopamine receptor antagonists cis-flupenthixol, pimozide or dompe…
Pharmacological analysis of the responsiveness of guinea-pig lung parenchymal strip to dopamine
1984
Abstract Responses to dopamine were examined in the guinea-pig isolated lung parenchymal strip. Complete cumulative concentration-response curves to dopamine exhibited a biphasic pattern with a small initial contraction at concentrations below 10(-5) M followed by a dose-dependent relaxation at higher concentrations. Phentolamine (10(-5) M) completely abolished the contractile component and enhanced sensitivity and maximal relaxation to dopamine. In the presence of phentolamine, propranolol antagonized the dopamine-induced relaxation (pA2 = 8.54 +/- 0.07). In the presence of propranolol (10(-6) M), dopamine produced a dose-related contraction displaced to the right by phentolamine. Incubati…
ACTIONS OF PROSTAGLANDIN E2 ON MYOCARDIAL MECHANICS, CORONARY VASCULAR RESISTANCE AND OXYGEN CONSUMPTION IN THE GUINEA-PIG ISOLATED HEART PREPARATION
1975
Abstract 1 In isolated, electrically driven (3 Hz) hearts of guinea-pigs the action of prostaglandin E2 on left ventricular pressure (LVP), oxygen consumption (Qo2) and coronary vascular resistance (CVR) was studied by establishing cumulative concentration-response curves. The hearts were perfused at a constant flow (10 ml/min) with Tyrode solution (Ca++ 1.8 mM) at 32 degrees C. 2 Under control conditions prostaglandin E2 (2.86 X10(-11) -1.43 X 10(-7) M) decreased LVP, QO2 and CVR in a concentration-dependent manner by maximally 27, 18 and 38%, respectively (P less than 0.05). 3 After reserpine pretreatment there were lower initial values for all parameters measured. The effect of prostagla…
INTERACTIONS OF ISOPRENALINE AND PROSTAGLANDIN E2 WITH RESPECT TO MYOCARDIAL CONTRACTILE FORCE, CORONARY VASCULAR RESISTANCE AND MYOCARDIAL OXYGEN CO…
1976
Left ventricular pressure (LVP), left ventricular pressure derivative (LV dp/dtmax), coronary vascular resistance (CVR) and myocardial oxygen consumption (Qo2) were measured simultaneously in isolated, electrically driven hearts of guinea-pigs at constant perfusion rate. 2 LVP, LV dp/dtmax, CVR and Qo2 were greatly decreased by either the addition of prostaglandin E2 (50 ng/ml) to the perfusion fluid or pretreatment of the animals with reserpine. 3 Isoprenaline (0.5 nM to 100 nM) induced increases in LVP, LV dp/dtmax and Qo2. In the presence of prostaglandin E2, there was a parallel shift of the isoprenaline concentration-response curve for LVP and LV dp/dtmax. This effect was not seen, aft…
Effects of alterations in sympathetic nervous activity on the severity of reperfusion-induced arrhythmias in anaesthetised rats.
1987
The effects of a number of interventions influencing sympathetic nervous activity on the severity of coronary artery reperfusion-induced arrhythmias in anaesthetised rats have been examined. Noradrenaline (0.1 microgram kg-1 min-1) reduced the mortality that usually occurred as a consequence of ventricular fibrillation. Isoprenaline (5 micrograms kg-1) did not significantly affect the severity of reperfusion-induced arrhythmias, although arrhythmias occurring during the 5-min period of ischaemia were exacerbated. The alpha-adrenoceptor antagonist nicergoline (0.25 and 0.5 mg kg-1 min-1) markedly suppressed both the ventricular tachycardia and fibrillation occurring upon release of the occlu…