Portal de Periódicos da CAPES

The effect of the vagus nerves on the bradycardia and ventricular arrhythmias induced by digitoxin and digoxin

1974; Elsevier BV; Volume: 28; Issue: 2 Linguagem: Inglês

10.1016/0014-2999(74)90281-7

1879-0712

Daniel G. Pace, John A. Quest, Richard A. Gillis,

Respiratory and Cough-Related Research

Both digitoxin and digoxin produced bradycardia when administered to intact animals. To evaluate the role of the vagus nerves in the bradycardia produced by these agents, comparable doses of both drugs were administered to chloralose-anesthetized cats with spinal cords transected. Digitoxin infusion (2μg/kg/min i.v.) to animals with intact vagi resulted in a heart rate decrease of 31±6.0 beats/min. Administration of the drug to cats with vagus nerves sectioned resulted in a heart rate decrease of 13±4.8 beats/min. No bradycardia occured in cats with sectioned vagus nerves and pretreated with atropine (1mg/kg i.v.). In contrast, digoxin administration (2μg/kg/min i.v.) to animals with intact vagus nerves did not produce a significant degree of cardiac slowing (-9.8±4.3 beats/min). In addition, vagotomy had no effect on the arrhythmogenic doses of either digitoxin or digoxin. These results indicate that the bradycardia produced by digitoxin but not digoxin is mediated by the cholinergic nervous system. These results also suggest that qualitative differences in the actions of cardiacglycosides may exist.