INCREASED SENSITIVITY OF THE RENAL VASCULATURE TO ADENOSINE IN STREPTOZOTOCIN-INDUCED DIABETES-MELLITUS RATS

Adenosine (ADO) has been implicated as a pathophysiological factor in contrast media (CM)-induced acute renal failure, which has been encoun tered more often in patients with diabetes and impaired renal function . Therefore, we studied the renal vascular response to exogenous and e ndogenous ADO in streptozotocin-induced diabetic rats. We found that e xogenous ADO (0.01-100 nmol), injected into the abdominal aorta, decre ased renal blood flow (RBF) in a dose-dependent manner. The dose-respo nse curve was shifted to the left by factor 30 in diabetic, compared w ith nondiabetic rats rats. Renal vascular response to endogenous ADO, assessed by postocclusive reduction of RBF after a 30-s renal artery o cclusion, was significantly enhanced (P < 0.001) in diabetic rats (75. 6 +/- 3.9%) compared with nondiabetic rats (36.5 +/- 2%). ADO A(1)-rec eptor blockade with 8-cyclopentyl-1,3-dipropylxanthine attenuated exog enous and endogenous ADO-induced renal vasoconstriction in both groups . We conclude that the ADO Al-receptor signal-transduction chain is al tered in diabetic animals and that the enhanced vasoconstrictive actio n of ADO could be involved in the kidney pathophysiology of diabetes m ellitus.