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

我们在未成熟家兔身上建立了慢性压力超载或容量超载的心脏作为先天性心脏病的原位模型。对未成熟大鼠过载的离体肥厚热进行灌注，研究其再灌注损伤的机制。首先，我们研究了细胞外钙浓度对全脑缺血后功能恢复的影响。其次，再灌注未成熟心脏心肌内pH值与Ca^<2+>收缩蛋白敏感性的关系。结果1)全缺血40min后再灌注开始时Ca^<2+>由1.75mM增加到2.5mM，改善了离体1周龄兔心脏的机械功能。2)Na^+/H^+抑制剂（氨基环内酯）虽有改善成人心脏机械功能的报道，但对未成熟再灌注心脏无显著影响。3)添加Cl^-/HCO3^-抑制剂（sit）对1周龄兔心脏再灌注无显著影响。4)Ca^<2+>增敏剂（匹莫苯丹）可显著改善未成熟兔再灌注心肌的收缩功能。5)我们改进了灌注系统，允许在^<32>P-NMR安装的25mm线圈中每4分钟检测到高能磷酸盐信号。

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.