Effect of alpha-adrenergic stimulation on prostacyclin and renin release in the rat kidney

The relationship between renin secretion and PGI₂ production, in response to intrarenal infusion of norepinephrine, was examined in the isolated perfused rat kidney. Infusion of norepinephrine in a dose which caused substantial vasoconstriction (100 ng/min), markedly increased urinary excretion of 6-keto PGF_1α, the stable derivative of PGI₂, without significantly altering renin secretion measured in the effluent perfusate. No change in urinary 6-keto PGF_1α occurred when vasoconstriction was prevented by infusing the alpha-adrenoceptor blocking drug phenoxybenzamine (2 × 10³ ng/min) alongside norepinephrine 100 ng/min). However, under these conditions there was marked stimulation of renin secretion which, as has been demonstrated previously, is mediated by a beta-adrenoceptor. There were significant increase in urine flow rates during both vasoconstrictor and non-vasoconstrictor infusions. These findings clearly indicate that in the rat kidney prostacyclin production and renin release in response to norepinephrine are dissociated.