EVIDENCE FOR A NORADRENERGIC INNERVATION TO ALPHA-1A-ADRENOCEPTORS IN RAT-KIDNEY

1 Experiments were undertaken to characterize the alpha1-adrenoceptor subtype mediating vasoconstrictor responses to periarterial noradrenergic nerve stimulation (PNS) in the isolated perfused kidney of the rat. 2 Vasoconstrictor responses to nerve stimulation were inhibited by prazosin (10 nM), 5-methyl-urapidil (30 nM), and nitrendipine (1 muM) but were resistant to inhibition by chloroethylclonidine (100 muM). 3 5-Methyl-urapidil (30 nM), chloroethylclonidine (100 muM) and nitrendipine (1 muM) did not inhibit the neuronal release of tritium from nerves loaded with [H-3]-noradrenaline. 4 The results suggest that renovascular alpha1A-adrenoceptors receive a noradrenergic innervation and that the innervated receptors are coupled to dihydropyridine-sensitive calcium channels.