Cardiac electrophysiologic effects of alinidine, a specific bradycardic agent, in the conscious dog: plasma concentration-response relations.

We studied the cardiac electrophysiologic effects of alinidine in conscious dogs. Sinus rate, corrected sinus recovery time (CSRT), and Wenckebach point (WP) were determined in 6 intact dogs. Atrial and ventricular rates, and atrial effective refractory period (AERP) were determined in 6 atrioventricular (AV)-blocked dogs. In both groups, we also measured blood pressure (BP) and plasma alinidine concentrations. Each dog received four intravenous (i.v.) injections of 0.5, 0.5, 1, and 2 mg/kg alinidine (hydrobromide) 30 min apart. At all doses, alinidine decreased sinus rate (< or = 43%) and ventricular rate (< or = 44%), but increased atrial rate (< or = 31%). It lengthened CSRT (< or = 71%) at the two highest doses and increased AERP (< or = 33%) and decreased WP (< or = 33%) at all doses. Alinidine did not modify mean BP at any dose in either group. Overall, these results indicate that alinidine exhibits electrophysiologic effects in conscious dogs that reflect antiarrhythmic potentials of this drug apart from its assumed antiischemic properties.