Role of Calcium Channels in the Protective Effect of Hydrogen Sulfide in Rat Cardiomyoblasts

f these authors contributed equally Abstract Background: Hydrogen sulfide contributes to the reduction of oxidative stress-related injury in cardiomyocytes but the underlying mechanism is still unclear. Aims: Here we investigated the role of voltage-operated calcium channels (VOCCs) as mediators of the beneficial effect of H 2 S against oxidative stress in cultured rat cardiomyoblasts (H9c2). Methods: Intracellular calcium signals were measured by fluorimetric live cell imaging and cell viability by colorimetric assay. Results: Treatment with H 2 S donor (NaHS 10 µM) or Nifedipine (10 µM) decreased resting intracellular calcium concentration (Ca) i , suggesting that L-type VOCCs are negatively modulated by H 2 S. In the presence of Nifedipine H 2 S was still able to lower (Ca) i , while co- incubation with Nifedipine and Ni 2+ 100 µM completely prevented H 2 S-dependent (Ca) i decrease, suggesting that both L-type and T-type VOCCs are inhibited by H 2 S. In addition, in the same experimental conditions, H 2 S triggered a slow increase of (Ca) i whose molecular nature remains to be clarified. Pretreatment of H9c2 with NaHS (10 µM) significantly prevented cell death induced by H 2 O 2 . This effect was mimicked by pretreatment with L-Type calcium channel inhibitor Nifedipine (10 µM). Conclusions: The data provide the first evidence that H 2 S protects rat cardiomyoblasts against oxidative challenge through the inhibition of L-type calcium channels.