CONCENTRATION DEPENDENCY OF THE RENAL VASCULAR AND RENIN SECRETORY RESPONSES TO ADENOSINE RECEPTOR AGONISTS

  • 1 January 1985
    • journal article
    • research article
    • Vol. 232  (1) , 189-193
Abstract
Exogenous adenosine inhibits renin secretion and can either vasoconstrict or vasodilate the renal vasculature in vivo. .mu.Mol concentrations of N6-cyclohexyl adenosine [CHA] and 5''-N-ethylcarboxamide adenosine, analogs which are relatively, selective for A1 and A2 adenosine receptors, respectively, tended to have opposite effects on both afferent arteriolar resistance and renin secretory rate in isolated rat kidneys perfused at constant pressure. Because the affinities of A1 and A2 receptors differ considerably, the concentration dependencies of the renal hemodynamic (perfusion pressure or prefusate flow, glomerular filtration rate, filtration fraction) and the renin secretory effects of adenosine, N6-cyclohexyl adenosine and 5''-N-ethylcarboxamide adenosine were studied. Both the renovascular and the renin secretory effects of CHA were biphasic; at sub .mu.mol concentrations, total and afferent arteriolar resistances were increased and renin secretion was inhibited. At higher concentrations, these effects were reversed or abolished. 5''-N-Ethylcarboxamide adenosine and adenosine decreased total and segmental (afferent and efferent) resistances and stimulated renin secretion. Evidently, A1 and A2 receptors mediate inhibition and stimulation of renin secretion, afferent arteriolar A1 and A2 receptors mediate constriction and dilation and efferent arteriolar A2 receptors mediate dilation.

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