REGULATION OF ADRENERGIC-RECEPTORS IN THE RAT-KIDNEY

Chronic daily application of (+/-)-isoprenaline induced a selective-do wn regulation of beta-adrenoceptors in the kidney: the concentration o f [H-3]dihydroalprenolol binding sites was significantly lowered by is oprenaline treatment while [H-3]prazosin and [H-3]rauwolsine binding, representing alpha(1)- and alpha(2)-adrenoceptors, respectively, was n ot markedly altered. Since the proportion of high- and low-affinity si tes for the non-selective alpha- but relatively beta(1)-selective agon ist (-)-noradrenaline remained constant and since in [3H]dihydroalpren olol competition experiments the high- and low-affinity site ratio fit ted well to the beta(1)/beta(2) relation, determined independently by employing ICI 118551 as a beta(2)-selective ligand, a parallel decreas e of both beta(1)- and beta(2)-adrenoceptor density can be concluded.