Changes in tissue alpha- and beta-adrenergic receptors in renal hypertension in the rat

Abstract

Myocardial membranes prepared from renal hypertensive rats contained reduced concentrations of both alpha- and beta-adrenergic receptors. The decrease in alpha-receptor concentration measured by [3H]-dihydroergocryptine binding was from 80 +/- 6 (SEM) to 52 +/- 2 fmol/mg. Beta-receptor concentration measured by 125I-iodohydroxybenzylpindolol binding also decreased by about half from 80 +/- 16 to 41 +/- 9 fmol/mg. The affinities of the receptors were unchanged. There was no change in either concentration or affinity of beta receptors in membranes prepared from the lungs or kidneys of these hypertensive rats. There results demonstrate that the observed receptor changes are tissue-specific. Cardiac adrenergic receptor alterations are therefore not part of a generalized adrenergic receptor decrease associated with elevated circulating plasma catecholamine concentrations, but probably reflect a specific increase in cardiac sympathetic drive.