SUPERSENSITIVE DILATOR RESPONSE TO NITROGLYCERIN BUT NOT TO ATRIAL-NATRIURETIC-PEPTIDE IN SPASTIC CORONARY-ARTERIES IN CORONARY SPASTIC ANGINA

It has been shown that there is the supersensitivity of the dilator ef fect of nitrovasodilators in the coronary arteries of patients with co ronary spastic angina. This study was aimed to elucidate its mechanism (s) by examination of dilator response of spastic coronary arteries to atrial natriuretic peptide (ANP), which is known to dilate arteries b y the same final common pathway through cyclic guanosine monophosphate (cGMP) as nitrovasodilators. Effects of infusion of nitroglycerin and ANP on epicardial coronary diameter of left coronary arteries were th us examined by quantitative coronary angiography in 20 patients with c oronary spastic angina, who had spasm in left coronary arteries, and i n 27 control subjects. Dilator response of coronary diameter to intrac oronary infusion of ANP (0.5 mu g/kg) was found to be comparable betwe en spastic coronary arteries and control arteries, whereas dilator res ponse to nitroglycerin (250 mu g) was enhanced in the spastic arteries compared with control arteries. The results indicate that spastic cor onary arteries exhibit supersensitive dilator response to nitroglyceri n but not to ANP. There is a possibility that dilator response to cGMP may be comparable between spastic and control coronary arteries and t hat soluble guanylate cyclase activity and/or conversion of nitric oxi de bioactivity from nitroglycerin may be enhanced in spastic coronary arteries. (C) 1997 by Excerpta Medica, Inc.