Direct effect of beta-adrenergic stimulation on renin release by the rat kidney slice in vitro

Controversy exists regarding the mechanism by which catecholamines stimulate renin secretion in vivo. A sensitive rat kidney slice system was utilized to study the direct effects of adrenergic agonists and antagonists on renin release in vitro. Catecholamines were protected from degradation by the addition of ascorbic acid to the incubation medium. Significant dose-related stimulation of renin release was observed with epinephrine and norepinephrine in concentrations from 1.5 times 10(-9) to 1.5 times 10(-7)M and with isoproterenol in concentrations from 2 times 10(-9) to 2 times 10(-7)M. No significant stimulation was seen with 10(-10)M concentrations of the three agents. Methoxamine (10(-6)M) stimulated renin release significantly (P less than 0.01). The stimulation observed with epinephrine, norepinephrine, or isoproterenol was blocked by d,l- and l-propranolol (2 times 10(-4)M) but not by d-ropranolol (2 times 10(-4)M) or phentolamine (9 times 10(-4)M). Methoxamine-induced stimulation was abolished by d,l-propranolol but not by phentolamine. These data that the in vitro kidney slice system is responsive to physiological concentrations of catecholamines when they are protected from degradation. The results further demonstrate a direct stimulatory role for beta-adrenergic agents on renin release and suggest that alpha-adrenergic effects seen in vivo are mediated indirectly by hemodynamic, vascular, or functional changes in the kidney.