Evidence for a noradrenergic innervation to alpha sub(1A)-adrenoceptors in rat kidney

Experiments were undertaken to characterize the alpha sub(1)-adrenoceptor subtype mediating vasoconstrictor responses to periarterial noradrenergic nerve stimulation (PNS) in the isolated perfused kidney of the rat. Vasoconstrictor responses to nerve stimulation were inhibited by prazosin, 5-methyl-urapidil, and nitrendipine but were resistant to inhibition by chloroethylchlonidine. 5-Methyl-urapidil, chloroethylclonidine and nitrendipine did not inhibit the neuronal release of tritium from nerves loaded with ( super(3)H)-noradrenaline. The results suggest that renovascular alpha sub(1A)-adrenoceptors receive a noradrenergic innervation and that the innervated receptors are coupled to dihydropyridine-sensitive calcium channels.