ABSTRACT
Eight types of peaks were revealed in the cardiac rhythm spectrum during acute experiments on vagotomized cats. Some peaks had no physiological nature and resulted from specificity of ECG processing by Fourier analysis, while others reflected myogenic reaction of the sinoatrial node (length-dependence of automaticity) to changes in venous return caused by respiratory-induced and other variations of the blood flow in the cardiovascular system.
Subject(s)
Electrocardiography , Heart Rate/physiology , Animals , Cats , Chloralose/administration & dosage , Fourier Analysis , Heart/innervation , Heart Rate/drug effects , Narcotics/administration & dosage , Pentobarbital/administration & dosage , VagotomyABSTRACT
Vagal influences on the heart were studied in narcotized cats, in which the cardiotropic effects of sympathetic nerves, heart rate, and pre- and afterload were excluded. Under these conditions vagus nerve exerted only a positive inotropic effect probably mediated by an unknown humoral factor.
Subject(s)
Heart/physiology , Myocardial Contraction/physiology , Vagus Nerve/physiology , Animals , CatsABSTRACT
In experiments on anesthetized cats, aconitine produced direct arrhythmogenic and cardiotoxic effects on the myocardium combined with indirect cardiotropic effects mediated via activation of extracardial nerves. Aconitine demonstrated pronounced cholinolytic properties and blocked vagal arrhythmogenic effect.
