Cellular Distribution and Function of Soluble Guanylyl Cyclase in Rat Kidney and Liver

Soluble guanylyl cyclase (sGC) catalyzes the biosyn- thesis of cGMP in response to binding of L-arginine-derived nitric oxide (NO). Functionally, the NO-sGC-cGMP signaling pathway in kidney and liver has been associated with regional hemodynamics and the regulation of glomerular parameters. The distribution of the ubiquitous sGC isoform 11 sGC was studied with a novel, highly specific antibody against the 1 subunit. In parallel, the presence of mRNA encoding both subunits was investigated by using in situ hybridization and reverse transcription-PCR assays. The NO-induced, sGC-de- pendent accumulation of cGMP in cytosolic extracts of tissues and cells was measured in vitro. Renal glomerular arterioles, including the renin-producing granular cells, mesangium, and descending vasa recta, as well as cortical and medullary inter- stitial fibroblasts, expressed sGC. Stimulation of isolated mes- angial cells, renal fibroblasts, and hepatic Ito cells with a NO donor resulted in markedly increased cytosolic cGMP levels. This assessment of sGC expression and activity in vascular and interstitial cells of kidney and liver may have implications for understanding the role of local cGMP signaling cascades.