[Effect of endothelin on the proliferation of aortic smooth muscle cells in normotensive and spontaneously hypertensive rats].

In order to examine the effect of endothelin (ET-1) as a growth factor, vascular smooth muscle cells were isolated from aortas of spontaneously hypertensive (SHR) and control (WKY) rats. Cell proliferation was determined by measurement of labelled 3H-thymidine incorporation in quiescent cells in presence of ET-1 alone or in association with another growth factor, insulin (INS). ET-1 alone (0.1 to 100 nM) increased slightly the growth of both types of cells. This effect was enhanced in presence of INS (0.1 to 10 micrograms/ml). SHR cells were more reactive than control ones. Activation of Na+/H+ exchange which is a necessary response for mitogenesis was dose dependently observed with increasing concentrations of ET-1 (0.1 to 100 nM) further confirming that ET-1 could act as a growth factor for vascular smooth muscle cells.