Differential expression of renal adenosine A1 receptors induced by acute renal failure

Abstract The distribution of renal adenosine A 1 receptors was investigated in rats with glycerol- or mercuric chloride (HgCl 2 )-induced acute renal failure. Receptors were localised by autoradiography using [ 3 H]8-cyclopentyl-1,3-dipropylxanthine ([ 3 H]DPCPX), a selective A 1 adenosine receptor antagonist. In saline-injected control animals, significant labelling with [ 3 H]DPCPX was detected in glomeruli, the inner stripe of outer medulla, and the inner medulla. Sixteen hours following induction of glycerol-induced acute renal failure (ARF), a 34% increase in labelling in glomeruli was noted compared to saline-injected controls, and by 48 hr, glomerular labelling had increased by 200%. In addition, 48 hr following glycerol injection, significant labelling was now detected in the cortical labyrinth and medullary rays whilst, in the inner medulla, labelling had decreased by 34%. By contrast to glycerol-induced ARF, the only significant change noted 48 hr following induction of HgCl 2 -induced ARF was a 39% decrease in labelling in the inner medulla. It is concluded that glycerol-induced ARF results in differential expression of renal adenosine A 1 receptors with increased expression in the cortex and reduced expression in the inner medulla. Increased density of A 1 receptors in glomeruli may account, at least in part, for the increased renal vasoconstrictor response to adenosine and depressed glomerular filtration rate noted previously in this type of acute renal failure.