Adenosine inhibits beta-adrenoceptor but not DBcAMP-induced renin release

The purpose of these studies was to assess the direct effect of adenosine on the renin release response to beta-adrenoceptor activation in vivo in the canine kidney. In an initial study, innervated, intrarenal beta-adrenoceptors were activated selectively via renal nerve stimulation in kidneys in which the alpha-adrenoceptor response to renal nerve stimulation had been blocked with phentolamine. Adenosine, infused directly into the renal artery (10 and 30 micrograms/min), significantly blunted the renin release response to renal nerve stimulation. However, adenosine also caused significant reductions in base-line glomerular filtration rate, sodium excretion rate, and filtration fraction. To eliminate these confounding effects of adenosine on renal function and to prevent changes in norepinephrine release due to prejunctional inhibition by adenosine, we also studied the effect of intrarenal infusions of adenosine on norepinephrine-induced renin release in the nonfiltering, alpha-adrenoceptor-blocked, canine kidney. In this model of beta-adrenoceptor activation, adenosine abolished the renin release response to intrarenal infusions of norepinephrine. In a final series of experiments, the effect of adenosine on the renin response to dibutyryl-adenosine 3',5'-cyclic monophosphate (cAMP) was examined in the nonfiltering, beta-adrenoceptor-blocked, canine kidney. In this model of cAMP-induced renin release, adenosine was ineffective in attenuating the renin release response. These data demonstrate that in vivo adenosine directly inhibits beta-adrenoceptor-mediated renin release by a mechanism that does not involve a reduction in the ability of cAMP to activate intracellular mechanisms leading to renin release.