Gene delivery of Kir6.2/SUR2A in conjunction with pinacidil handles intracellular Ca 2+ homeostasis under metabolic stress

ABSTRACT Metabolic injury is a complex process affecting various tissues, with intracellular Ca 2+ loading recognized as a common precipitating event leading to cell death. We have recently observed that cells overexpressing recombinant ATP‐sensitive K + (K ATP ) channel subunits may acquire resistance against metabolic stress. To examine whether, under metabolic challenge, intracellular Ca 2+ homeostasis can be maintained by an activator of channel proteins, we delivered Kir6.2 and SUR2A genes, which encode K ATP channel subunits, into a somatic cell line lacking native K ATP channels. Hypoxia‐reoxygenation was simulated by application and removal of the mitochondrial poison 2,4 dinitrophenol. Under such metabolic stress, Ca 2+ loading was induced by Ca 2+ influx during hypoxia and release of Ca 2+ from intracellular stores during reoxygenation. Delivery of Kir6.2/SUR2A genes, in conjunction with the K ATP channel activator pinacidil, prevented intracellular Ca 2+ loading irrespective of whether the channel opener was applied throughout the duration of hypoxia‐reoxygenation or transiently during the hypoxic or reoxygenation stage. In all stages of injury, the effect of pinacidil was inhibited by the selective antagonist of K ATP channel, 5‐hydroxydecanoate. The present study provides evidence that combined use of gene delivery and pharmacological targeting of recombinant proteins can handle intracellular Ca 2+ homeostasis under hypoxia‐reoxygenation irrespective of the stage of the metabolic insult.—Jovanović, N., Jovanović, S., Jovanović, A., Terzic, A. Gene delivery of Kir6.2/SUR2A in conjunction with pinacidil handles intracellular Ca 2+ homeostasis under metabolic stress. FASEB J. 13, 923–929 (1999)