Dexamethasone sensitizes soluble guanylate cyclase in the rat renal glomeruli

We measured capability for guanosine 3',5'-cyclic monophosphate (cGMP) synthesis by isolated renal glomeruli from steroid-treated rats. Glomeruli obtained from animals treated with dexamethasone showed 5-fold higher sensitivity to sodium nitroprusside (SNP) than glomeruli from deoxycorticosterone- or saline-treated rats. Similar increase in activity of the glomerular soluble guanylate cyclase in response to SNP was observed. Dexamethasone markedly suppressed stimulatory effect of atrial natriuretic factor (ANF) on glomerular cGMP synthesis suggesting existence of cross-regulatory system(s) generating cGMP in renal glomeruli. We presume that glucocorticoid-induced hyperfiltration can be partially caused by sensitization of soluble guanylate cyclase to the nitric oxide, a potent natural dilatory agent.