Effect of nifedipine on neuropeptide Y-induced coronary vasoconstriction in anesthetized dogs.

The coronary vasoconstrictor effects of neuropeptide Y (NPY) were confirmed in anesthetized closed-chest dogs. This NPY-induced vasoconstriction was not affected by alpha- or beta-adrenergic blockers and nifedipine given into the perfusion circuit abolished the constriction. After intracoronary nifedipine administration, coronary flow exceeded the control level within 60 sec, then returned to a level between the control value before NPY and the lowest value elicited by NPY after 10 min. When nifedipine was given systemically before NPY, the peak response to NPY was attenuated, suggesting a preventive effect of nifedipine on the NPY-induced coronary vasoconstriction. Since NPY is found in the hearts of many species, including man, NPY may cause coronary vasospasms. An effect on NPY-induced coronary vasoconstriction of nifedipine may be compatible with the beneficial clinical effects of this drug.