Effect of the New Specific Bradycardic Agent AQ-A39 (Falipamil) on Coronary Collateral Blood Flow in Dogs

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Abstract
The effect of two doses (0.5 and 1.0 mg/kg i.v.) of a new specific bradycardic agent, AQ-A39 (5,6-dimethoxy-2-[3-([α-(3,4,-dimethoxy)phenylethyl]methy[amino)propyl]phthalimidine hydrochloride). on three indices of collateral function—retrograde pressure, retrograde flow, and tissue blood flow (radioactive microspheres)— was studied in anesthetized dogs following acute occlusion of the left anterior descending coronary artery. AQ-A39 produced a significant (p < 0.05) dose-related decrease in heart rate without any other hemodynamic changes. Retrograde flow and subendocardial blood flow were significantly increased by the lower dose of AQ-A39, whereas retrograde pressure, retrograde flow, and midmyocardial and subendocardial flow were increased by the higher dose. Atrial pacing to the control heart rate eliminated the beneficial effects of AQ-A39 on collateral function. These results suggest that an increase in collateral perfusion may be one mechanism by which AQ-A39 alleviates myocardial ischemia