Gene delivery of Kir6.2/SUR2A in conjunction with pinacidil handles intracellular Ca2+ homeostasis under metabolic stress

Metabolic injury is a complex process affecting various tissues, with intra cellular Ca2+ loading recognized as a common precipitating event leading to cell death. We have recently observed that cells overexpressing recombinan t ATP-sensitive K+ (K-ATP) channel subunits may acquire resistance against metabolic stress, To examine whether, under metabolic challenge, intracellu lar Ca2+ 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-reoxygenati on was simulated by application and removal of the mitochondrial poison 2,4 dinitrophenol, Under such metabolic stress, Ca2+ loading was induced by Ca 2+ influx during hypoxia and release of Ca2+ from intracellular stores duri ng reoxygenation. Delivery of Kir6.2/SUR2A genes, in conjunction with the K -ATP channel activator pinacidil, prevented intracellular Ca2+ loading irre spective 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 t he selective antagonist of K-ATP channel, 5-hydroxydecanoate. The present s tudy provides evidence that combined use of gene delivery and pharmacologic al targeting of recombinant proteins can handle intracellular Ca2+ homeosta sis under hypoxia-reoxygenation irrespective of the stage of the metabolic insult.