Comparison of Cardiovascular Responses to the Bradycardic Drugs, Alinidine, AQ-A 39, and Mixidine, in the Anesthetized Dog

Publisher Website
Google Scholar
Abstract
Cardiovascular responses to 3 bradycardic drugs, alinidine, AQ-A 39 and mixidine, were studied in open-chest, anesthetized dogs. All 3 drugs produced a dose-related decrease in heart rate at 0.3-10 mg/kg, i.v. At 3.5 mg/kg i.v., spontaneous heart rates were decreased by 59 .+-. 7, 52 .+-. 6, and 39 .+-. 6 beats/min with alinidine, AQ-A 39 and mixidine, respectively. The sinus node was an important site of action, because direct injection of alinidine, AQ-A 39 or mixidine to the sinus node via the sinus node artery (50 .mu.g) elicited a negative chronotropic response. On systemic administration, total peripheral resistance was significantly increased with alinidine, significantly decreased with AQ-A 39, and not affected with mixidine. Increases in stroke volume accompanied bradycardic responses to AQ-A 39 and mixidine, and were prevented when heart rate was held constant by electrical pacing. Despite the production of similar effects on heart rate, AQ-A 39 differed from alinidine and mixidine in that it did not depress cardiac contractility in dogs with spontaneous heart rates. All 3 drugs were effective and relatively selective in reducing heart rate; however, responses at the systemic vasculature and myocardium differed.

This publication has 16 references indexed in Scilit: