A Role for Adenosine Calcium and Ischemia in Radiocontrast-Induced Intrarenal Vasoconstriction

Abstract

These studies were designed to test the hypothesis that adenosine and calcium are important in mediating radiocontrast-media-associated reduction in renal blood flow (RBF) in the dog. Intravenous verapamil (V) and diltiazem (DTZ) infusion significantly attenuated the magnitude of the vasoconstrictor response observed after each intrarenal contrast media (CM) injection. (First injection: -47 +/- 8% control vs. -14 +/- 3% V, p less than 0.03; -38 +/- 4% control vs. -19 +/- 3% DTZ, p less than 0.02. Second injection: -33 +/- 6% control vs. -12 +/- 1% V, p less than 0.03; -32 +/- 5% control vs. -17 +/- 2% DTZ, p less than 0.03. Third injection: -32 +/- 6% control vs. -11 +/- 5% V, p less than 0.03; -38 +/- 5% control vs. -10 +/- 5% DTZ, p less than 0.02). Furthermore, V and DTZ almost completely abolished the increase in renal vascular resistance (RVR) induced by each CM administration. Theophylline also significantly attenuated the magnitude of the vasoconstrictor response observed after CM injection (first injection: -31 +/- 3% control vs. -12 +/- 3% theophylline, p less than 0.05; second injection: -26 +/- 3% control vs. -12 +/- 3% theophylline, p less than 0.03). Similarly, theophylline blunted the increase in RVR induced by CM injection. In addition, theophylline inhibited exogenous adenosine-induced decrease in RBF (-61 +/- 10% and -26 +/- 1% decrease in RBF without and with theophylline, respectively). In contrast, dipyridamole significantly enhanced the vasoconstriction induced by CM (first injection: 25 +/- 3% control vs. 49 +/- 4% dipyridamole; second injection: 31 +/- 3% control vs. 48 +/- 4% dipyridamole p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)