Effects of adenosine on renin release from isolated rat glomeruli and kidney slices

Abstract

Adenosine produced by the macula densa cells in response to changes in the tubular NaCl-concentration has been suggested to inhibit renin release in vivo. In order to test this suggestion we studied: a) incubated kidney cortical slices (KS) which contain both the macula densa and the entire afferent arteriole; b) superfused single microdissected glomeruli (LAG) without macula densa but with the afferent artericole preserved; and c) superfused batches of selected glomeruli (SAG) containing only the juxtaglomerular cells closest to the glomerulus. For superfusion and incubation a bicarbonate Ringer solution was used. The specificity of the renin release process was validated by measuring adenylate kinase as a marker for cytoplasmatic leak. Adenosine (10 μg/ml) halved basal renin release from incubated KS as compared to controls (Pn=8, 8). Renin release from LAG stimulated by calcium depletion was also inhibited (Pn=8, 9) whereas basal release was not affected (n=6, 12). No effect was detected neither on basal nor on calcium stimulated renin release from SAG. We conclude that adenosine inhibits renin release in vitro by a mechanism independent of a functioning nephron, and which involves only the JG-cells located in the afferent arteriole at some distance from the glomerulus.