[The effect of diltiazem on atrioventricular conduction in dogs].

The effect of diltiazem on atrioventricular conduction was studied in pentobarbital anesthetized dogs, conscious dogs, and atropine pretreated conscious dogs. In anesthetized dogs diltiazem administration resulted in diminished heart rate and aortal pressure, as well as prolongation of the functional refractory period of the AV node and of AV conductance. The effective refractory period of the atria and intraatrial conductance were not affected. The function of the AV node was comparable in the three groups studied. An anticholinergic action of diltiazem affecting the AV node has thus to be excluded. The recorded slight increase in heart rate in conscious dogs may be accounted for by the activation of baroreceptors induced by decreased aortal pressure.