Regulation of renal adenosine A(1) receptors: effect of dietary sodium chloride

The influence of dietary NaCl on the regulation of renal adenosine A(1) rec eptors was investigated in the rat. Renal membranes from rats fed on a diet low (0.04%) in NaCl showed a 46% increase in B-max for the binding of [H-3 ]-1,3-dipropyl-8-cyclopentylxanthine ([H-3]DPCPX), a selective adenosine A( 1) receptor antagonist, compared to membranes from rats fed on a normal die t (0.4% NaCl). Conversely, a high NaCl diet (4.0%) resulted in a 37% decrea se in B-max. Levels of renal adenosine A(1) receptor mRNA were 65% lower in rats on a high salt diet. Autoradiographic studies showed that, for the in ner medullary collecting ducts, a low NaCl diet resulted in a 30% increase in [H-3]DPCPX binding with a 39% decrease noted in rats maintained on a hig h salt diet. The results indicate that changes in adenosine A(1) receptor d ensity may represent a novel mechanism whereby the kidneys adapt to changes in salt load. (C) 1999 Elsevier Science B.V. All rights reserved.