Actions of prostacyclin (PGI2) on adrenergic neuroeffector transmission in the rabbit kidney.

In the Tyrode's perfused rabbit kidney PGI2 (1.3 x 10(-8)-3.3 x 10(-7)M) dose-dependently inhibited vasoconstrictor responses to sympathetic nerve stimulation, as did PGE2. The dose-effect curve of the two compounds differed, making PGI2 the less potent in the low concentration and the more potent in the high. PGI2 also inhibited the vasoconstrictor response to exogenous noradrenaline, but it had no effect on transmitter release. The main metabolite of PGI2, 6-keto-PGF1 alpha, was ineffective both on noradrenaline release and on vascular responses to nerve stimulation or exogenous noradrenaline. It is suggested that PGI2, if a significant renal prostaglandin, may modulate renal neuroeffector transmission post-junctionally, thereby forming a complement to the prejunctional action of PGE2.