Effects of nifedipine on myocardial energy balance in experimental coronary vasoconstriction and occlusion.

The effect of nifedipine on the myocardial energy demand--supply imbalance caused by vasopressin-induced vasoconstriction, coronary occlusion, and their combined action was studied in isolated perfused rabbit hearts using the method of NADH fluorometry. Nifedipine (0.015 microgram/ml) completely prevented the development of NAD/NADH imbalance caused by coronary vasospasm. The role of vasoconstriction as an addition to coronary occlusion was very small in the development of regional energy imbalance and the vasopressin-induced detrimental effect was prevented by nifedipine. Energy imbalance caused by the occlusion alone was only partially improved by the drug. There was a delay in the development of energy imbalance and reduction in the final degree of NADH fluorescence response to the occlusion (97 +/- 8% vs. 66 +/- 9%, p less than 0.05).