Blockade of Transient Receptor Potential Vanilloid 4 Enhances Antioxidative Activity and Attenuates Hypoxia/Reoxygenation Injury in Cardiomyocytes: Involvement of Akt/Nrf2/ARE

Abstract

Antioxidative stress provided the cardioprotective effects in myocardial ischemia/reperfusion (I/R). Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable nonselective cation channel and widely expressed in the cardiovascular system. We previously demonstrated blockage of TRPV4 attenuates hypoxia/reoxygenation (H/R) induces Ca2+ influx and decreases reactive oxygen species (ROS) release, and finally alleviates injury in cardiomyocytes. The current study focused on whether blockade of TRPV4 reduced the injury via the antioxidative activity during H/R and explored the molecular mechanisms in cardiomyocytes. Our results reveal that H/R induced cell injury as evidenced by the cell viability, the release of lactate dehydrogenase (LDH) and apoptosis, which were obviously alleviated by a selective TRPV4 blocker HC-067047 or specific TRPV4-siRNA. Moreover, H/R also increased the contents of ROS and malondialdehyde (MDA) and decreased the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), which were reversed by HC-067047 or specific TRPV4-siRNA. Furthermore, HC-067047 treatment increased the expression of P-Akt, and the translocation of nuclear factor E2-related factor 2 (Nrf2) and related antioxidant response element (ARE) mainly including SOD, GSH-Px and hemeoxygenase-1(HO-1) after H/R. In addition, the Akt inhibitor, LY294002, absolutely hampered these cardioprotective effects of HC-067047. Finally, we confirmed the antioxidative stress roles of blockade of TRPV4 in myocardial I/R or application of exogenous H2O2. In conclusion, inhibition of TRPV4 exerts protective effects against oxidative stress induced cardiomyocyte injury possibly related to the up-regulated Akt/Nrf2/ARE pathway.