Maintenance for the positive inotropic effect in ischemic myocardial mitochondria and the development of new cardiac drug.

心脏线粒体被认为在心脏的泵送作用中起着重要作用。线粒体（约占心肌体积的30%）与心肌细胞形成密切的共生关系，通过能量生产/利用和离子运输机制维持心肌的基本功能。因此，我们采用^<31>P-NMR和荧光法测量线粒体中ALP、PCr等能量货币相关物质和H^+ Ca^<2+>、Na^+等各种离子。1998年，我们发现Na-H交换抑制剂对缺血/再灌注损伤的保护作用部分是由于线粒体水平的Ca^<2+>-悖论。含有Na^+或K^+的灌注液使线粒体pH值升高，表明质子与线粒体膜中这些一价阳离子之间存在反端口机制（Na- h, K- h）。预负荷异常高Ca^<2+>的线粒体基质Ca^<2+1>通过生理浓度的再灌注或pH为6.5的酸化灌注而升高。这一发现将解释线粒体水平的Ca^<2+>-悖论。1999年，我们得出结论，线粒体中存在eNOS， NO可能通过抑制Ca^<2+>流入线粒体而对缺血后心脏再灌注损伤起重要的保护作用，否则线粒体会被O_2^-损伤。EPR法检测离体线粒体中活性氧和NO的生成。自发生成NO的SNAP或no5预处理完全抑制线粒体Ca^<2+> (Cam)摄取。即使在Langendorff制剂中，抑制Cam内流的药物也能改善缺血后的收缩力。因此，由NO供体（FK409）外源性提供的NO负责心脏保护作用，可能是在再灌注过程中直接作为氧自由基清除剂。红花5HT衍生物或5HT_<2A>-阻滞剂的抗氧化作用可能在心肌缺血再灌注损伤中发挥重要作用，并与NO密切相关。少

Cardiac mitochondria are recognized to play an essential role in the pumping action of the heart. Mitochondria (about 30% volume) and heart muscle cells form an intimate symbiotic relationship the basic myocardial functions of which are maintenance via energy production/utilization and ion transport mechanisms. Therefore, we used ^<31>P-NMR and fluorometry to measure energy currency-related substances of ALP, PCr etc and various ions of H^+ Ca^<2+>, Na^+ in mitochondria. In 1998, we found that the protective effects of Na-H exchange inhibitor against ischemia/reperfusion injury are due in part to the Ca^<2+>-paradox at the mitochondrial level. The elevation of mitochondrial pH by the perfusate containing Na^+ or K^+ indicate the existence of antiport mechanisms (Na-H, K-H) between protons an these monovalent cations in the mitochondrial membrane. Matrix Ca^<2+1> in mitochondria preloaded with abnormally high Ca^<2+> were elevated by reperfusion of either with physiological concentratio … More n of Ca^<2+> or acidified perfusate of pH 6.5. This finding will interpret the Ca^<2+>-paradox at mitochondria level. In 1999, we concluded that eNOS exits in mitochondria, and that NO may play an important protective role against reperfusion cardiac injury after ischemia, by inhibiting the Ca^<2+> influx into mitochondria which are otherwise damaged by O_2^-. The production of reactive oxygen species and NO in isolated mitochondria was detected by EPR.Pretreatment with SNAP or NOC5, which spontaneously generate NO, completely inhibited the mitochondrial Ca^<2+> (Cam) uptake. The agents that inhibit Cam influx improve contractility even in Langendorff preparations after ischemia. Therefore, NO exogenously supplied by NO donor (FK409) was responsible for the cardioprotective action, presumably by acting directly as an oxygen radical scavenger during reperfusion. Antioxidant effects of 5HT derivatives from safflower or 5HT_<2A>-blocker increasing the NO basal level might play an important role in ischemia-reperfusion injury hearts in close relation with NO. Less