Effect of beta adrenergic blockade on renin response to renal nerve stimulation.

Abstract

A B S T R A C T The ability of dl-propranolol to block renin secretion in response to various extrarenal stimuli, such as hemorrhage and hypoglycemia, has been inter- preted to indicate the presence of an intrarenal beta re- ceptor regulating renin release. However, two problems complicate this interpretation: (a) the stimuli have effects outside the kidney, and (b) dl-propranolol has a local anesthetic, as well as a beta adrenergic blocking, action. In the present study, the effects of a purely in- trarenal stimulus, in the form of renal nerve stimulation (RNS), on renin secretion was examined. The effects of dl-propranolol (anesthetic and beta-blocking ac- tivity), l-propranolol (beta-blocking activity only), and d-propranolol (local anesthetic activity only) on the renin response to RNS were examined. In a control group of animals, two sequential RNS increased mean renin secretion from 401 to 1,255 U/min (P < 0.25) and from 220 to 2,179 U/min (P <0.01). In a second group the first RNS increased renin secretion from 201 to 1,181 U/min (P < 0.01), but after dl-propranolol was given RNS did not significantly alter renin secretion (33 to 55 U/min). In a third group the initial RNS in- creased renin secretion from 378 to 1,802 U/min (P < 0.025), but after l-propranolol was given RNS had no significant effect on renin secretion (84 to 51 U/min). A fourth group of dogs showed a rise in renin secretion from 205 to 880 U/min (P < 0.001) in response to the first RNS, while the second RNS, given after an infu- sion of d-propranolol, caused a rise in renin secretion from 80 to 482 (P < 0.005). The nature of the electrical stimulus was consistent in all groups and caused no detectable changes in renal or systemic hemodynamics or in urinary electrolyte excretion. The results, there-