Effects of ICI 118.551, a selective beta-2 adrenergic blocking agent on the guinea pig cardic excitability and ventricular fibrillation threshold

In isolated guinea pig perfused hearts ICI 118.551, a selective beta 2 adrenoceptor antagonist, induced transient ventricular extrasystoles. Following the termination of the perfusion, a very significant increase of both the ventricular fibrillation threshold and the refractory periods were measured. In guanethidine pretreated hearts, ICI 118.551 failed to induce premature beats. At the same time the fibrillation threshold and refractory periods exhibited a very significant decrease. The perfusion of equimolecular concentration of metoprolol, a beta-1-adrenoceptor antagonist, and (+) propranolol, a quinidine-like compound, induced, in most experimental settings, similar results as ICI 118.551. Thus, besides its beta-2-adrenoceptor antagonist properties, ICI 118.551 presented other pharmacological actions

Effects of zopiclone on blood glucose level, serum lipid concentration and clot lysis time normoglycemic and normolipidemic rats

In normoglycemic and normolipidemic rats the i.p. injection of zopiclone induced an acceleration of fibrinolysis in a dose-dependent bell shaped manner and various changes of the blood glucose level. Total lipids, total cholesterol and triglyceride serum levels remained unaffected by doses of 1.25, 2.5 and 15.0 mg/kg, with the exception of the medium dose (5.0 mg/kg) and the next dose (10.0 mg/kg) which lowered them very significantlly

The influance of intracerebroentricular administration of (±)propanol and(±)verapamil on experimental myocardial ischemia and necrosis in rats

In albino rats, infarctoid myocardial lesions were produced by intraperitoneal (i.p.) administration of isoproterenol (75 mg/kg, during 3 days). In other groups, the descending anterior left coronary artery was ligated. In both experimental settings, the intracerebroventricular (i.c.v.) administration of ( ± ) propranolol (100-200-300 μ g/animal/day, during 7 days) or ( ± ) verapamil (40-80-160 μ g/animal/day, during 7 days) afforded a significant protection (with the exception of the lowest dose) on the investigated parameters: arrhythmias, ischemic zone (in coronary ligated rats), lactate dehydrogenase and aspartate aminotransferase activity of the serum, focal necrosis (in isoproterenol treated rats). This protective activity is lower than that afforded by i.p. administered (±) propranolol (5 mg/kg, during seven days) or (±) verapamil (5 mg/kg, during seven days). From these data it may be concluded that (±) propranolol and (±) verapamil have a protective action on the experimental myocardial ischemia and necrosis in rats, not only when the drugs come in direct contact with the heart, but also acting upon the central nervous system

Central arrhythmogenic effects of N-methyl-D-aspartate (NMDA) in anesthetized rats: influence of the denervation of the carotid-sinus baroreceptors on the susceptibility to arrhythmias

Wir besprechen ein Demonstrationsexperiment zur Induktion, das zu paradoxen Spannungsmessungen führt, und zeigen die Problematik einer rein formalen Erklärung auf. Um ein tieferes Verständnis zu ermöglichen, stellen wir ergänzende Versuchsanordnungen vor. Diese erlauben es, die Verteilung induzierter elektromotorischer Kräfte in homogenen wie inhomogenen Leitern nachzuweisen. Sie machen deutlich, was man mit Voltmetern an Anordnungen mißt, die zeitlich veränderlichen elektromagnetischen Feldern ausgesetzt sind

Effects of the intracerebroventricular administration of ketamine on centrogenic arrhythmias in anesthetized rats.

In urethane anesthetized rats the icv (lateral cerebral ventricle) administration of ketamine, at the highest utilized doses, induced bradypnea and sinus bradycardia in spontaneously breathing rats. Moreover, it partially antagonized the arrhythmogenic activities of sodium glutamate and sodium aspartate, as well as desipramine and ouabain. From these results, we conclude that ketamine had an inhibitory effect on the centrogenic arrhythmias not only acting at the level of NMDA subtype receptor, but also at beta 1 adrenergic central receptors. Moreover at high doses, ketamine can also induce centrogenic arrhythmias in spontaneously breathing rats