Author(s): ShimokawaH, Tomoike H, Nabeyama S, Yamamoto H, Ishii Y
In a swine model of coronary artery spasm, the pathogenetic role of coronary atheroscierosis was examined. Following endothelial balloon denudation of the left circumflex coronary artery (LCX), male miniature swine were fed a laboratory chow diet containing 2% cholesterol. Although there was no difference in the extent of coronary vasoconstrictive response to histamine, serotonin, and ergonovine between the left anterior descending coronary artery (LAD) and the LCX before the denudation, a constrictive response was significantly augmented along the denuded portion of the LCX 1 and 3 months after the denudation. Augmented vasoconstrictive responses to phenylephrine were never evidenced. Histamine was the most potent vasoactive agent, and coronary artery spasm was provoked repeatedly by intracoronary or intravenous administration of histamine in the presence or absence of cimetidine. The spasm was provoked only in the denuded portion of the LCX, the same area which was angiographically normal before the occurrence of the spasm. Histologically, atherosclerotic changes were predominant along the denuded portion of the LCX. Topologic correlation was suggested between the site of the spasm and the site of coronary atherosclerosis. It is concluded that in this swine model of coronary artery spasm, atherosclerotic changes may be an important causative factor, in terms of an activation of multiple receptor-operated calcium channels in the coronary artery.