Remodelling of Kir6. x after cardiac Tschemia and its functional consequence

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ATP-sensitive KィイD1+ィエD1 channels (KィイD2ATPィエD2) are hetromeric octmer composed of inwardly rectifying KィイD1+ィエD1 channels (Kir6. x) and sulfonylurea receptors (SURx). We have previously reported that amongst the above molecules, Kir6.1 was selectively up-regulated after cardiac ischemia. However, its functional consequences remain unclear. We therefore constucted a cDNA of Kir6.1-Kir6.2 tandem fusion protein (TDM), and coexpressed it with SUR2A in COS7 cells. TDM possessed an intermediate single channel conductance between Kir6.1 and Kir6.2 In the absence of intracellular MgィイD12+ィエD1, TDM and Kir6.2 showed identical ATP sensitivity, whereas in the presence of MgィイD12+ィエD1, the ATP sensitivity of TDM was significantly lower. Thereby, the cardioprotective role of TDM may be enhanced.