cinanserin and Arrhythmias--Cardiac

Rabbits were used to study the inhibitory effect of analogous electro-acupuncture on the experimental arrhythmias, i.e. hypothalamic stimulation-induced ventricular extrasystole (HVE). The result revealed that HVE, which was due to an increased cardiac sympathetic activity, could be inhibited by deep peroneal nerve stimulation with an electrical current of low frequency and low intensity. Such effect is related to endogenous opioid peptides and serotonin in the arcuatus area, the periaqueductal gray and and the medial medulla. The acupuncture correction of arrhythmias may have the same mechanism.

Topics: Acupuncture Therapy; Animals; Arrhythmias, Cardiac; Blood Pressure; Cardiac Complexes, Premature; Chemoreceptor Cells; Cinanserin; Electric Stimulation Therapy; Electrocardiography; Heart; Hypothalamus; Medulla Oblongata; Microinjections; Morphine; Naloxone; Norepinephrine; Periaqueductal Gray; Pressoreceptors; Rabbits; Serotonin; Sympathetic Nervous System; Vagus Nerve

Topics: Animals; Arrhythmias, Cardiac; Cinanserin; Cyproheptadine; Digitalis Glycosides; Female; Guinea Pigs; Heart Rate; In Vitro Techniques; Male; Methysergide; Ouabain; Serotonin Antagonists; Time Factors

The present study was performed to determine whether pharmacological blockade of serotonin receptors would counteract digitalis-induced ventricular arrhythmias. The effect of the serotonin receptor blocking drugs, methysergide, cinansersin, and cyproheptadine on ventricular arrhythmias produced by ouabain was studied in anesthetized dogs. Each of the three serotonin receptor blocking drugs given as a bolus i.v. injection of 1.5--3.0 mg/kg produced an antiarrhythmic effect. In addition, methysergide administered in the above doses to cats intoxicated with deslanoside, restored an abnormal ventricular arrhythmia to either sinus or junctional rhythm. Methysergide, administered to cats intoxicated with deslanoside but pretreated with p-chlorophenylalanine, exerted an antiarrhythmic effect in less than half of the animals tested. These data indicate that serotonin antagonists are effective in counteracting digitalis-induced ventricular arrhythmias and support the notion that a serotonergic mechanism may be mediating the arrhythmogenic effect of digitalis.

Topics: Animals; Arrhythmias, Cardiac; Cinanserin; Cyproheptadine; Dogs; Female; Fenclonine; Hemodynamics; Male; Methysergide; Ouabain; Serotonin