Role of P2X7 Receptor on Hypoxia-Induced Vascular Endothelial Growth Factor Gene Expression in H9c2 Rat Cardiomyocytes

Purinergic P2X7 receptors (P2X7Rs) may provide cardioprotection against ischemic heart disease. Cardiac angiogenesis is an endogenous adaptive response of hypoxic cardiomyocytes, mediated by vascular endothelial growth factor (VEGF) via hypoxia-inducible factor-1α (HIF-1α). The study aimed to determine whether P2X7Rs can regulate cardiac pro-angiogenic signaling in hypoxic H9c2 cardiomyocytes by modulating the angiogenic factor VEGF through HIF-1α genes. H9c2 rat cardiomyocytes were exposed to hypoxia alone or in combination with the P2X7R antagonist A740003. Subsequently, ATP levels and LDH activity were measured. The expression of P2X7R, HIF-1α, and VEGF was detected. Intracellular ATP level was significantly lower in hypoxia cardiomyocytes, whereas extracellular ATP, HIF-1α, and LDH levels were significantly higher in hypoxic cardiomyocytes. These effects were associated with increased P2X7R and VEGF gene expressions. Pretreatment with A740003 reversed HIF-1α and VEGF expressions in hypoxic cardiomyocytes. The findings suggest that P2X7Rs regulate pro-angiogenic signaling in hypoxic cardiomyocytes through the HIF-1α/VEGF pathway. Thus, the P2X7R-mediated HIF-1α/VEGF pathway may represent a novel approach to stimulating angiogenesis and preventing heart failure in ischemic heart disease.