MAGNESIUM INHIBITS THE RESPONSES TO NEUROPEPTIDE-Y IN THE RABBIT CORONARY-ARTERY

Neuropeptide Y (NPY) has been shown to cause direct vasoconstriction of coronary arteries in many species, including dogs, rabbits and man [1-3], which is selectively inhibited by calcium-channel blocking agents [1]. Recently, NPY has also been reported to inhibit the relaxation to noradrenaline in isolated rabbit coronary arteries [3], but the composition of the Krebs solution described in this study indicated that it contained no magnesium. Since magnesium is known to be a physiological antagonist of calcium and to have a profound influence on the contraction of coronary vascular smooth muscle [4, 6], we examined the importance of magnesium in modulating both the direct vasoconstrictor response to NPY and the NPY-induced inhibition of relaxation to noradrenaline, using ring preparations of rabbit circumflex coronary artery. © 1991.