RESUMO
Intrarenal adenosine concentration is threefold greater in the one-kidney, one clip hypertensive rat compared with normotensive animals. Since exogenously administered adenosine may increase renal blood flow by direct vasodilation, inhibition of renin release, or prejunctional interruption of adrenergic neurotransmission, these studies examined whether endogenous intrarenal adenosine maintains renal blood flow distal to renal arterial stenosis. Administration of theophylline, which blocks the direct vasodilating effect of adenosine and antagonizes the inhibitory effect of adenosine on renin release and sympathetic neurotransmission, resulted in marked renal vasoconstriction in one-kidney, one clip hypertensive animals. This theophylline-induced renal vasoconstriction was markedly attenuated by angiotensin II blockade with saralasin and was unchanged by renal denervation or beta 1-adrenergic blockade with atenolol. These findings indicate that the marked renal vasoconstriction in one-kidney, one clip hypertension during theophylline administration is mainly mediated by angiotensin II, is to a lesser degree due to inhibition of adenosine-induced vasodilation, and is independent of sympathetic influences. These data suggest that endogenous interstitial adenosine preserves renal blood flow in one-kidney, one clip hypertension mainly by inhibiting renin release.