INHIBITION BY ALPHA-ADRENOCEPTOR AGONISTS OF RENIN RELEASE INVITRO

A variety of α-adrenergic agonists encompassing a broad range of concentrations were used to investigate the existence and nature of a putative α-adrenergic mechanism inhibitory to renin release, which may operate at the level of the juxtaglomercular apparatus. For this purpose rat renal cortical tissue incubated in vitro was used. Concentrations of noradrenaline, adrenaline and methoxamine of 10-6, 10-5, 10-4 and 10-3 M caused significant dose-related inhibition of renin release. The inhibition of release by these doses was reversed completely by 10-4 phentolamine. In contrast, phenylephrine, oxymetazoline and clonidine did not inhibit renin release. The results support the concept of an α-adrenergic mechanism inhibitory to renin release and show that high concentrations of α-andrenergic agonist are required for its operation in vitro. The manner in which this inhibitory mechanism affects renin release under physiological circumstances remains to be demonstrated. © 1979.