AJP - Renal Physiology, Vol 244, Issue 6 633-F638, Copyright © 1983 by American Physiological Society
Action of adenosine on cyclic 3',5'-nucleotides in glomeruli
H. E. Abboud and T. P. Dousa
Recent in vivo studies indicated that adenosine has a profound effect on
glomerular dynamics and renal circulation. Because its effect in nonrenal
tissues is frequently mediated by adenosine 3',5'-cyclic monophosphate
(cAMP), we examined adenosine's effect on cyclic nucleotides in rat kidney.
Incubation of tissue slices from renal cortex or medulla with 0.1 mM
adenosine resulted in marginal or no increase in cAMP. In isolated
glomeruli, adenosine caused a marked and dose-dependent (10(-6) to 10(-4)
M) increase in cAMP accumulation. Inosine, a deaminated metabolite of
adenosine, had no effect on cAMP levels in glomeruli. No distinct effect of
adenosine on cAMP was observed in cortical tubules under the same testing
conditions. An increase in cAMP levels in glomeruli elicited by adenosine
was blocked by theophylline, a known inhibitor of adenosine receptors. In
contrast, theophylline enhanced rather than decreased the stimulation of
cAMP accumulation in glomeruli by serotonin. Dipyridamole, a proposed
inhibitor of cellular uptake of adenosine, did not inhibit but rather
enhanced cAMP accumulation in glomeruli in response to adenosine. In the
present experiments adenosine did not influence guanosine 3',5'-cyclic
monophosphate levels in either glomeruli or other tested preparations of
renal tissue. These results provide the first experimental evidence that
adenosine stimulates cAMP accumulation in glomeruli and suggest that this
effect is probably due to action on the adenosine receptor on the cell
surface. Our observations raise the possibility that some of the effects of
adenosine in glomerular cells may be mediated via cAMP accumulation.
