2.Pharmacological mechanism Organic nitrates NO guanylyl cyclase cGMP↑ cGMP dependent protein kinase intracellular Ca2+ vascular smooth muscle relaxation2.Pharmacological mechanism Organic nitrates Organic nitrates NO guanylyl guanylyl cyclase cyclase cGMP cGMPdependent protein dependent protein kinase intracellular Ca intracellular Ca2+ 2+ vascular smooth muscle relaxation vascular smooth muscle relaxation