Nicardipine releases sustained coronary arterial constriction induced by acetylcholine in the rhesus monkey

In five rhesus monkeys (Macaca mulatta) the vascular bed of the left anterior descending coronary artery (LAD) was perfused at constant pressure with autologous blood. Nicardipine (1-30 micrograms), a dihydropyridine calcium antagonist when injected into the LAD, increased LAD flow without producing significant changes in other cardiohemodynamic variables. With continuous infusions of acetylcholine into the LAD, the flow decreased by about 34% of the basal value. Under these conditions, intra-LAD nicardipine produced an increase in LAD flow almost to the same extent as in the control. The effects of nicardipine were qualitatively similar to those of other calcium antagonists observed in previous experiments and indicate that nicardipine would be useful as an antianginal drug.