Supersensitivity of the renal tubule to catecholamines in the chronically denervated canine kidney.

Experiments were performed on anesthetized dogs to study whether or not renal tubules of the chronically denervated kidney show supersensitivity toward circulating catecholamines. In one kidney the influence of plasma catecholamines was inhibited by intrarenal administration of the alpha adrenergic receptor blocker phenoxybenzamine (POB, 2 micrograms/min), and renal parameters of the infused kidney were compared to those of the contralateral noninfused organ. Before POB infusion urine flow (V), urinary sodium and potassium excretion (UNa V, UKV) as well as clearance of inulin and PAH (GFR, CPAH) were similar in infused and contralateral kidneys in all groups studied. In dogs (n = 8) with two innervated kidneys POB infusion elevated V and UNa V by 53 +/- 13% and 102 +/- 34% (p less than 0.05). In dogs (n = 8) with acute bilateral renal denervation POB administration failed to alter any of the measured parameters. In contrast, V and UNaV from chronically denervated kidneys (n = 7) were increased after POB infusion by 40 +/- 9% and 103 +/- 34% (p less than 0.05). Glomerular filtration rate, CPAH and UKV were not changed by alpha adrenoceptor blockade in any of the groups. In an additional group of animals (n = 8) acute unilateral renal denervation increased V and UNaV to a significantly higher extent (by 282 +/- 85% and 330 +/- 106%) than POB administration did in the innervated kidney and elevated UKV (44 +/- 10%), too.(ABSTRACT TRUNCATED AT 250 WORDS)