INFLUENCE OF CONTRAST-MEDIA ON THE RESPONSE OF RAT RENAL-ARTERIES TO ENDOTHELIN AND NITRIC-OXIDE - INFLUENCE OF CONTRAST-MEDIA

RATIONALE AND OBJECTIVES. Contrast media (CM) such as diatrizoate megl umine (DTZ) or iohexol can cause renal vasoconstriction in vivo, and t his may initiate CM-induced nephropathy, Endothelin-1 (ET-1), a vasoco nstrictor, and nitric oxide, a vasodilator, are key modulators of rena l circulation. We tested the hypothesis that CM enhances arterial resp onses to ET-1, or diminishes responses to nitric oxide. METHODS. A vid eo dimension analyzer continuously recorded changes in diameter of iso lated, pressurized rat interlobar renal arteries (200-400 mu m diamete r) superfused with combinations of Chi, ET-1, nitric oxide, and other vasoactive agents. RESULTS. Superfusion of arteries with 3.3% DTZ, but not with 3.3% iohexol, enhanced their sensitivity to ET-1 by approxim ately twofold, as assessed by shifts in concentration-response curves. Both DTZ and iohexol decreased the sensitivity of arteries to nitric oxide by approximately threefold. Neither DTZ nor iohexol affected art erial sensitivity to other vasoconstrictors (phenylephrine, potassium) or vasodilators (forskolin, diltiazem), CONCLUSIONS. Diatrizoate megl umine and iohexol may induce or augment renal vasoconstriction in part by causing selective alterations in arterial sensitivity to ET-1 and to nitric oxide.