MYOCARDIAL PROTECTION AND POTASSIUM MOVEMENT

心肌缺血导致细胞内离子失衡(Na&lt；@d1+@&gt；d1过载；K&lt；@d1+@&gt；d1丢失)。我们推测，在缺血后心肌中，温氧合血停搏液(WOBC)增加心肌耗氧量(VO&lt；@D22@&gt；D2)，可能增强Na&lt；@d1+@&gt；d1/K&lt；@d1+@&gt；d1泵的活性，这可能有助于细胞内离子失衡的恢复。为了验证这一点，我们测定了心脏手术热OBC期间Na&lt；@d1+@gt；d1/K&lt；@d1+@&gt；D2泵活性的温度依赖性，并探讨了VO&lt；@d22@&gt；D2与阳离子运动的关系。方法：(A)用全细胞钳制技术(RAMP：+50~-130 mV)记录18ﾟ、28ﾟ和28ﾟC时豚鼠心肌细胞哇巴因敏感电流(Ip)。(B)44例心脏手术患者在18ﾟC每30分钟进行一次体外循环，最后在35ﾟ-37ﾟC(Na&lt；@d1+@&gt；d1：134.8(sy.+-)。[)0.4；K&lt；@d1+@&gt；d1：18.7()sy.+-。[)0.1mmo1/L)。在输注最后一次温血时，冠脉流出物为Sa…冠状静脉窦(CS)更多(5-8个不同点/例)。Na&lt；@d1+@&gt；d1或@d1+@&gt；d1的移动以其浓度差([阳离子]&lt；@D2CS@&gt；D2减去[阳离子]&lt；@D2OBC@&gt；D2)和VO&lt；@D22@&gt；D2通过OBC溶液和CS出水的含氧量之差来评价。阳离子移动效率(Ek，K&lt；@d1+@d1；d1；d2)通过在K&lt；@d1+@&gt；d1移动-VO&lt；@d22@&gt；D2关系中使用线性回归分析计算斜率来评估。结果：(A)37ﾟC时的Ip大于18ﾟC时的Ip(114.3±-)；[)17.2对22.7()SY+-。在-40 mV时，分别为1.2 pA)。(B)较大的VO；d2与[Na&lt；@d1+@&gt；d1]差值的较大正值和[K&lt；@d1+@&gt；d1；d1]差值的较大负值有关，提示在最后一个温暖的OBC.Ek(0.227-0.019 mmol/mlO&lt；@D22@&gt；d1)期间，能量依赖的跨肌膜阳离子运动(向外的Na&lt；@d1+；@d1；d1；D2)随缺血时间延长而减少(23~214min)。结论：氧合停搏液中可能存在能量依赖性的阳离子运动，有助于心肌细胞内Na&d1+d1超载和K&lt；@d1+&gt；d1的恢复。缺血时间的延长可能降低心肌耗氧量与阳离子运动的效率。较少

Myocardial ischemia results in intracellular ionic imbalance (Na<@D1+@>D1 overload ; K<@D1+@>D1 loss). We hypothesize that warm oxygenated blood cardioplegia (warm OBC) in the post-ischemic myocardium, incresing myocardial oxygen consumption (VO<@D22@>D2), may enhance Na<@D1+@>D1/K<@D1+@>D1 pump activity, which could contribute to recovery from the intracellular ionic imbalance. To test this, we determined temperature dependency of Na<@D1+@>D1/K<@D1+@>D1 pump activity and investigated the relationship between VO<@D22@>D2 and cation movement during warm OBC in cardiac surgery. Methods : (A) ouabain sensitive current (Ip) was measured at 18ﾟ, 28ﾟ, and 28ﾟC by whole-cell clamp technique (ramp : +50--130 mV) using Guinea-pig ventricular myocytes. (B) 44 patients undergoing cardiac surgery received OBC every 30 min at 18ﾟC and finally at 35ﾟ-37ﾟC (Na<@D1+@>D1 : 134.8(]SY.+-。[)0.4 ; K<@D1+@>D1 : 18.7(]SY.+-。[)0.1 mmol/L). During the infusion of the final warm OBC,the coronary effluent was sa … More mpled (5-8 different points/patient) from the coronary sinus (CS). Na<@D1+@>D1 or K<@D1+@>D1 movement was assessed by its concentration difference ( [cation] <@D2CS@>D2 minus [cation] <@D2OBC@>D2) and VO<@D22@>D2 by the difference of oxygen content between the OBC solution and the CS effluent. Cation movement efficiency (Ek, K<@D1+@>D1 movement per unit volume of VO<@D22@>D2) was assessed by calculating a slope using linear regression analysis in the K<@D1+@>D1 movement-VO<@D22@>D2 relationship. Results : (A) Ip was greater at 37ﾟC than at 18ﾟC (114.3(]SY.+-。[)17.2 vs 22.7(]SY.+-。[)1.2 pA at -40 mV,respectively). (B) The greatre VO<@D22@>D2 was associated with the greater positive value of the [Na<@D1+@>D1] difference and the greater negative value of the [K<@D1+@>D1] difference, suggesting energy dependent transsarcolemmal cation movement(outward Na<@D1+@>D1 ; inward K<@D1+@>D1)during the final warm OBC.Ek (0.227-0.019 mmol/ml O<@D22@>D2) decreased with prologation of the ischemic period (23-214 min). Conclusion : There may be energy dependent cation movement during oxygenated cardioplegia, contributing to recovery of the myocardium from the intracellular Na<@D1+@>D1 overload and K<@D1+@>D1 loss. Prolongation of the ischemic period might reduce the effeciency between myocardial oxygen consumption and cation movement. Less