Attenuated Desensitization of β-Adrenergic Receptor by Water-Soluble N-Nitrosamines That Induce S-Nitrosylation Without NO Release

Rationale: The clinical problem of loss of beta-adrenergic receptor (beta-AR) response, both in the pathogenesis of heart failure and during therapeutic application of beta-agonists, is attributable, at least in part, to desensitization, internalization, and downregulation of the receptors. In the regulation of beta-AR signaling, G protein-coupled receptor kinase 2 (GRK2) primarily phosphorylates agonist-occupied beta-ARs, and this modification promotes desensitization, internalization, and downregulation of beta-ARs. It has been demonstrated that GRK2 is inhibited by its S-nitrosylation. However, compounds that induce S-nitrosylation, such as S-nitrosoglutathione, simultaneously generate NO, which has been demonstrated to operate for cardiovascular protection. Objective: We examine whether S-nitrosylation without NO generation inhibits desensitization of beta(2)-AR by GRK2. We thus aim to synthesize compounds that specifically induce S-nitrosylation. Methods and Results: We have developed water-soluble N-nitrosamines that have S-nitrosylating activity but lack NO-generating activity. These compounds, at least partly, rescue beta-AR from desensitization in HEK293 cells expressing FLAG-tagged human beta(2)-AR and in rat cardiac myocytes. They inhibit isoproterenol-dependent phosphorylation and internalization of beta(2)-AR. Indeed, they nitrosylate GRK2 in vitro and in cells, and their S-nitrosylation of GRK2 likely underlies their inhibition of beta(2)-AR desensitization. Conclusions: Compounds that induce S-nitrosylation without NO release inhibit GRK2 and attenuate beta(2)-AR desensitization. Developing water-soluble drugs that specifically induce S-nitrosylation may be a promising therapeutic strategy for heart failure. (Circ Res. 2013;112:327-334.)