title: Towards an understanding of the mechanism of action of cyclic AMP and cyclic GMP in smooth muscle relaxation.
abstract: Cyclic GMP (cGMP) mediates the relaxing action of a variety of vasodilator drugs and endogenous vasodilator substances. Cyclic AMP (cAMP) mediates relaxation by beta-adrenergic agonists as well as other activators of adenylate cyclase. Both second messengers appear to reduce the concentration of intracellular Ca2+ in vascular smooth muscle cells, thus affecting relaxation. The presence of cGMP-dependent protein kinase in vascular smooth muscle cells is required for the reduction of Ca2+ by cAMP and cGMP, suggesting that this enzyme mediates the relaxing effects of both cyclic nucleotides. Although the specific substrate proteins for cGMP-dependent protein kinase are not well characterized in vascular smooth muscle, new evidence indicates that Ca2(+)-ATPase activation by phosphorylation of phospholamban by the kinase may underlie the mechanism of action of cyclic-nucleotide-dependent relaxation.
authors.affiliation: Department of Pharmacology, College of Medicine, University of South Alabama, Mobile.
authors.forename: T M
authors.initials: TM
authors.lastname: Lincoln
authors.forename: T L
authors.initials: TL
authors.lastname: Cornwell
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology*; D006152:Cyclic GMP / Q000494:pharmacology*; D006801:Humans; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D011494:Protein Kinases / Q000502:physiology; D013379:Substrate Specificity
chemical_list: D000242:Cyclic AMP; D011494:Protein Kinases; D006152:Cyclic GMP