Effects of endothelin 1 on phosphate transport in brush border membrane vesicles

Endothelin is the most potent vasoconstrictive agent released from endothelial and many other types of cells. It has been reported that endothelin has physiological effects on the rat kidney, especially on the renal proximal tubules. We investigated the role of endothelin 1 in the renal brush border membrane. The V(max) of P(i) uptake by brush border membrane vesicles (BBMV) in the endothelin-1-treated group was significantly greater than that in the control group. There were no significant changes in apparent K(m) values between the two groups. To define the direct effect of endothelin 1 on P(i) transport of BBMV, BBMV from normal rats were incubated with endothelin 1 in vitro. The P(i) uptake by BBMV incubated with endothelin 1 did not differ from that by BBMV incubated with a salt solution as a control. These results suggested the probability of the presence of endothelin 1 receptor in the proximal tubules. Administration of the endothelin 1 might increase the P(i) reabsorption by BBMV according to changes in the capacity of the transporter.