Stimulation of the Na+, K+ pump and the (Na+, K+, Cl-) cotransport system by endothelin-1 in cultured vascular smooth muscle cells: involvement of cyclo-oxygenase products.

: The effect of endothelin (ET-1) on vascular smooth muscle cell Na+ and K+ regulation was studied in the A10 cultured cell line. In contrast with other vasoconstrictors, ET-1 was able to strongly stimulate both the Na+, K+ pump and the (Na+, K+, Cl-) cotransport system at concentrations higher than 10(-10) M. This did not appear to reflect a direct interaction with the transport proteins because ET-1 was without effect on the same transport systems in human red cells. Indomethacin, at concentrations of 10(-5) M, was able to counteract the pump and cotransport stimulation by ET-1. These results suggest that the potent vasoconstrictive action of ET-1 induces a negative feedback mechanism via a cyclo-oxygenase product, which enhances the ability of vascular smooth muscle cells to regulate Na+ and K+ contents.