Effects of angiotensin II and vasopressin on human smooth muscle cells in vitro

Arterial smooth muscle cell hyperplasia is a histopathological marker of both hypertension and the initial stages of atherogenesis. In order to determine if vasoactive agents could promote arterial smooth muscle cell proliferation, two potent pressor hormones, angiotensin II and vasopressin, were tested in cell culture. Either one of these agents was added daily to cultures of human aortic smooth muscle cells maintained in homologous serum (HS) or fetal bovine serum (FBS). After 7 days, angiotensin II significantly enhanced cell proliferation in both types of sera. While vasopressin was found to be inhibitory in FBS, it also stimulated cell growth in HS. Furthermore, both peptides in HS induced an increase in average cell size. Comparative studies were conducted with human uterine smooth muscle cells and 3T3 mouse fibroblasts in order to determine the specificity of the growth effects for human vascular smooth muscle. The above in vitro studies suggest that angiotensin II and vasopressin, by modulating both number and size of arterial smooth muscle cells, may play a direct and until now unexpected role in the development of chronic vascular disease in man.