Study on Ca^<2+> sensitivity of reperfusion hypertrophied immature heart

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We developed chlonic pressure overloaded or volume overloaded heart on immature rabbits as a in situ model of congenital heart desease. The isolated hypertrophied heats subjected to overload were perfused and studied the mechanism of reperfusion injury in immature herat. was stuied Firstly, we studied effects of extracellular calcium concentrations on functional recovery after global ischemia. Secondly, the relation between intracardiac pH and Ca^<2+> sensitivity of contractile proteins in reperfused immature hearts.Results1)Increase of Ca^<2+> from 1.75mM to 2.5mM at the initiation of reperfusion after 40 min of global ischemia improved mechanical function of isolated one-week old rabbit hearts.2)Na^+/H^+ inhibiter (amirolide), reported to improve mechanical function of adult heart, showed no remarkable effect on immature reperfused hearts.3)No significant effect has also seen in addition of Cl^-/HCO3^- inhibiter (SITS) on reperfused one-week old rabbit hearts.4)Ca^<2+> sensitizer (pimobendan) improved dramatically contractile function of reperfused immature rabbit herats.5)We modified perfusion system to allow that high energy phosphates signal can be detected at each 4 min in ^<32>P-NMR mounted 25mm coil.