Regulation of cyclic GMP synthesis and the interactions with calcium

The formation of cyclic GMP (cGMP) by guanylate cyclase, and the properties of the soluble and particulate isoenzymes, are reviewed. Regulation of guanylate cyclase and cGMP accumulation in intestinal mucosa and vascular smooth muscle with and without endothelium are summarized. The effects of E. coli heat-stable enterotoxin, nitrovasodilators, endothelium-dependent vasodilators, and atrial natriuretic factors in these systems are discussed. A potential role for free radicals, Ca, and unsaturated fatty acids in cGMP synthesis is reviewed. These tissue systems (intestinal mucosa and vascular smooth muscle with or without intact endothelium) are presented as model systems and as examples of the regulation of cGMP accumulation in a single cell type by peptides, drugs, and cell-cell interactions that are required to generate cGMP with a hormone or drug.