Assays for S -Nitrosothiols and S -Nitrosylated Proteins and Mechanistic Insights Into Cardioprotection

Abstract

Gender differences in the incidence of cardiovascular disease may be ascribed at least in part to the protective effects of estrogen through both long-term and rapid (“nongenomic”) actions.1 Nitric oxide (NO), generated by endogenous cardiac NO synthases (NOS; NOS1 or neuronal NOS [nNOS], NOS2 or inducible NOS, NOS3 or endothelial NOS), plays a major role in both normal cardiac physiology and cardioprotection (particularly myocardial ischemia/reperfusion injury; see the Figure),2 and the article by Lin et al3 in this issue of Circulation contributes to growing evidence that the cardioprotective functions of estrogen are conveyed in significant part by NO. A rapidly expanding body of studies indicates that NO acts in most cellular contexts largely through the covalent modification of protein Cys thiols (to generate an S -nitroso [SNO]-protein, designated S -nitrosylation),4 and recent analyses using a new generation of analytical approaches (see the Table) both confirm original measurements of SNO-proteins that have been long-standing sources of controversy in the field and point to important roles for S -nitrosylation in NO-derived cardioprotection (see the Figure).3,5,6 Figure. NO-based mechanisms for preconditioning in ischemia/reperfusion injury. Accumulating evidence suggests a role for NO/SNO in estrogen and adrenergic receptor–mediated and statin-induced preconditioning in ischemia/reperfusion injury. Protein S -nitrosylation, resulting from increased NOS expression and activity and altered subcellular localization, appears to be a principal mediator of these effects. View this table: Table. Methodologies for the Detection and Absolute or Relative Quantification of SNO-Proteins and Other S -Nitrosothiols Article see p 245 In the myocardium, endothelial NOS is associated primarily with sarcolemmal caveolae and perhaps β-arrestin, and endothelial NOS–derived NO influences β-adrenergic receptor stimulation of myocardial contractility,7 at least in part through S -nitrosylation and inhibition of the L-type Ca2+ channel5 and G-protein receptor kinase 2.8 In contrast, nNOS …