Hydrogen Sulfide Regulates Na⁺/H⁺ Exchanger Activity via Stimulation of Phosphoinositide 3-Kinase/Akt and Protein Kinase G Pathways

Abstract

Intracellular pH (pH i ) is an important endogenous modulator of cardiac function. Inhibition of Naϩ /H ϩ exchanger-1 (NHE-1) protects the heart by preventing Ca 2ϩ overload during ischemia/reperfusion. Hydrogen sulfide (H 2 S) has been reported to produce cardioprotection. The present study was designed to investigate the pH regulatory effect of H 2 S in rat cardiac myocytes and evaluate its contribution to cardioprotection. It was found that sodium hydrosulfide (NaHS), at a concentration range of 10 to 1000 M, produced sustained decreases in pH i in the rat myocytes in a concentration-dependent manner. NaHS also abolished the intracellular alkalinization caused by trans-(Ϯ) -3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]benzeneacetamide methane-sulfonate hydrate (U50,488H), which activates NHEs. Moreover, when measured with an NHCl 4 prepulse method, NaHS was found to significantly suppress NHE-1 activity. Both NaHS and cariporide or [5-(2-methyl-5-fluorophenyl)furan-2-ylcarbonyl]guanidine (KR-32568), two NHE inhibitors, protected the myocytes against ischemia/reperfusion injury. However, coadministration of NaHS with KR-32568 did not produce any synergistic effect. Functional study showed that perfusion with NaHS significantly improved postischemic contractile function in isolated rat hearts subjected to ischemia/reperfusion. Blockade of phosphoinositide 3-kinase (PI3K) with 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), Akt with Akt VIII, or protein kinase G (PKG) with (9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg: 3Ј,2Ј,1Ј-kl]pyrrolo[3,4-i][1,6]]enzodiazocine-10-carboxylic acid, methyl ester (KT5823) significantly attenuated NaHS-suppressed NHE-1 activity and/or NaHS-induced cardioprotection. Although KT5823 failed to affect NaHS-induced Akt phosphorylation, Akt inhibitor did attenuate NaHS-stimulated PKG activity. In conclusion, this work demonstrated for the first time that H 2 S produced cardioprotection via the suppression of NHE-1 activity involving a PI3K/Akt/PKG-dependent mechanism.

The role of gasotransmitters NO, H2S and CO in myocardial ischaemia/reperfusion injury and cardioprotection by preconditioning, postconditioning and remote conditioning

“…Moreover, H 2S produced delayed cardioprotection via KATP/PKC-dependent induction of COX-2 expression and via NO-induced COX-2 activation (Hu et al, 2008b), inhibition of oxidative stress and activation of superoxide dismutase (SOD) . The mechanism accounting for H2S cardioprotective activities when it is administered prior to sustained ischaemia in isolated hearts involves a PI3K/Akt/PKG-dependent mechanism (Hu et al, 2011), contribution of KATP/PKC/ERK1/2 and PI3K/Akt pathways (Hu et al, 2008a), and expression of heat shock protein 72 (Bliksoen et al, 2008).…”

“…Furthermore, NaHS significantly increased cell viability, percentage of rod-shaped cells and myocyte contractility (Hu et al, 2008b). A rapid, time-dependent phosphorylation of JNK was observed in cultured rat neonatal cardiomyocytes, whereas NaHS inhibited this early phosphorylation of JNK, concluding that the early JNK inhibition during reperfusion is associated with H2S-mediated protection against cardiomyocyte apoptosis (Shi et al, 2009).Perfusion with NaHS significantly improved postischaemic contractile recovery (Hu et al, 2011), decreased myocardial infarct size and improved left ventricular (LV) contractile function Bliksoen et al, 2008;Hu et al, 2008a). Treatment of rat isolated hearts with NaHS, 10 min prior to the onset of coronary occlusion, resulted in a concentration-dependent limitation of infarct size (Johansen et al, 2006).…”

“…Moreover, H 2S produced delayed cardioprotection via KATP/PKC-dependent induction of COX-2 expression and via NO-induced COX-2 activation (Hu et al, 2008b), inhibition of oxidative stress and activation of superoxide dismutase (SOD) . The mechanism accounting for H2S cardioprotective activities when it is administered prior to sustained ischaemia in isolated hearts involves a PI3K/Akt/PKG-dependent mechanism (Hu et al, 2011), contribution of KATP/PKC/ERK1/2 and PI3K/Akt pathways (Hu et al, 2008a), and expression of heat shock protein 72 (Bliksoen et al, 2008).However there is controversy over the involvement of mitoKATP channels in the cardioprotective activity of H2S. Bian et al (2006) showed that blockade of mitoKATP channels with 5-hydroxydecanoic acid had no effect on the cardioprotection afforded by exogenous H2S, suggesting that contrary to the mechanism of classic PC, mitoKATP channels most probably do not play a major role in the cardioprotection afforded by H2S.…”

Emerging role of hydrogen sulfide-microRNA crosstalk in cardiovascular diseases

“…I/R injury leads to increased cardiomyocyte apoptosis (81). H 2 S reduces reactive oxygen species (ROS) associated with I/R injury as well as decreases in cardiomyocyte apoptosis during ischemia (36,56,70,81,135,141,161) (Table 1). A major complication following I/R injury is the occurrence of cardiac arrhythmias (37).…”

A Fast Hydrogen Sulfide–Releasing Donor Increases the Tumor Response to Radiotherapy

“…By noticing that low pHe itself had profound impact on cancer cell proliferation, we questioned whether NaHS treatment was able to exacerbate the acidic stress experienced by cancer cells at low pHe. Indeed, it was recently evidenced that, besides its ability to enhance glycolysis, H 2 S also impairs the activity of pH regulators in cancer cells, leading to the intracellular accumulation of acid and reduction of pHi (31,32). It is also known that pHi must be kept in a narrow range, otherwise cell-cycle progression and biosynthetic processes are compromised (33).…”