In vivo cardioprotection by S-nitroso-2-mercaptopropionyl glycine

Abstract

The reversible S-nitrosation and inhibition of mitochondrial complex I is a potential mechanism of cardioprotection, recruited by ischemic preconditioning (IPC), S-nitrosothiols, and nitrite. Previously, to exploit this mechanism, the mitochondrial S-nitrosating agent S-nitroso-2-mercaptopropionyl glycine (SNO-MPG) was developed, and protected perfused hearts and isolated cardiomyocytes against ischemia-reperfusion (IR) injury. In the present study, the murine left anterior descending coronary artery (LAD) occlusion model of IR injury was employed, to determine the protective efficacy of SNO-MPG in vivo. Intraperitoneal administration of 1 mg/kg SNO-MPG, 30 min. prior to occlusion, significantly reduced myocardial infarction and improved EKG parameters, following 30 min. occlusion plus 2 or 24 hr. reperfusion. SNO-MPG protected to the same degree as IPC, and notably was also protective when administered at reperfusion. Cardioprotection was accompanied by increased mitochondrial protein S-nitrosothiol content, and inhibition of complex I, both of which were reversed after 2 hr. reperfusion. Finally, hearts from mice harboring a heterozygous mutation in the complex I NDUSF4 subunit were refractory to protection by either SNO-MPG or IPC, suggesting that a fully functional complex I, capable of reversible inhibition is critical for cardioprotection. Overall, these results are consistent with a role for mitochondrial Snitrosation and complex I inhibition in the cardioprotective mechanism of IPC and SNO-MPG in vivo.

Site-Mapping of In Vitro S-nitrosation in Cardiac Mitochondria: Implications for Cardioprotection

“…In the mitochondrial respiratory chain, the main source of energy production in cardiac tissue, 11 novel SNO-sites were mapped to the subunits of complexes I-III, including seven modified residues located in six different subunits of complex I. Previous reports have shown that Complex I is S-nitrosated in preconditioning, and that cardioprotection may stem from reduced production of harmful reactive oxygen species (5,7,8,13). The sitespecific information provided here will now allow this hypothesis to be tested.…”

Cardioprotective PKG-independent NO signaling at reperfusion

“…However, the latter possibility seems unlikely, since Wort did not affect SNAP's protection in the present study either. The nitrosylating agent S-nitroso-2-mercaptopropionyl glycine given at reperfusion mimics IPC's protection in mouse heart (32), and a PKGindependent action of NO has been proposed to inhibit permeability transition pore formation in mitochondria after IPC [for review see Burwell and Brooks (5)]. In summary, it is not…”

Redox Regulation of Mitochondrial Function

“…Similarly, in studies of intact hearts, inhibition of complex I (with rotenone) during ischemia preserved mitochondrial cardiolipin and cytochrome c content (246), suggesting a role for ETC leak in cardiolipin oxidation and a possible target to prevent cardiolipin oxidation. Other therapeutic means to regulate ETC leak are being developed, including S-nitrosating compounds, that were discussed previously (306,336), and cationic plastoquinone derivatives (392). The function of GPx-4 to limit specifically mitochondrial phospholipids oxidation has also been explored, as discussed next.…”