Endothelin has a number of actions in the kidney, and there is growing evidence that whenever renal function is compromised, endothelin production as well as its binding to specific receptors is altered. Thus research on the role of endothelin in both renal function and dysfunction has provided some important information.

The effect of the novel nonpeptide endothelin (ET) receptor antagonist, ( ± )-SB 209670, on the renal effects of the high osmolar tri-iodinated ionic contrast media, Hypaque, was evaluated in anesthetized dogs in the presence or absence of the cyclooxygenase inhibitor, indomethacin (10 mg/kg, i.v.). Hypaque alone (5 ml/kg, i.v.) resulted in a marked diuresis and natriuresis but little change in either renal blood flow or renal vascular resistance. When the ET receptor antagonist, ( ± )-SB 209670, was infused into the renal artery at a dose that inhibited ET-induced renal vasoconstriction, Hypaque resulted in a significant increase in renal blood flow and decrease in renal vascular resistance. In the presence of indomethacin, Hypaque caused a significant increase in renal vascular resistance which was abolished by ( ± )-SB 209670. The data indicate that the radiocontrast media, Hypaque, can cause renal vasoconstriction which may be mediated by ET.

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