Parasympathetic effects on electrophysiologic properties of cardiac ventricular tissue.

摘要: The physiologic importance of parasympathetic influence on the sinoatrial and atrioventricular nodes is well established, but modulation ventricular function remains controversial. Recognized effects muscarinic cholinergic stimulation automaticity repolarization, ability agonists to antagonize catecholamine in ventricle proposed mechanisms for these are described. Anatomic studies have demonstrated a great abundance nerve endings association with conducting system. Stimulation vagus or addition suppresses most species antagonizes isoproterenol-induced action potential shortening isoproterenol-restored slow response potentials. In vivo, interactions between sympathetic nervous systems occur at multiple levels. Muscarinic inhibit release norepinephrine from terminals, catecholamine-stimulated adenylate cyclase activity alter cyclic guanosine monophosphate (GMP) possibly adenosine (AMP) Evidence also presented that, electrical might pathophysiologic milieu responsible initiation termination certain arrhythmias. Vagal influences appear be protective against digitalis-induced arrhythmias experimental acute myocardial infarctions. human beings, there appears tonic vagal tone terminates types tachycardia. evidence supports role altering function.