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.