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缺血后心室功能减低(myocardial stunning)的发生机制迄今尚不明了。本实验以 Lang-cndorff 法在离体灌流的大鼠心脏,研究了全心缺血20min 及再灌注40min 后心肌 Ca~(2+)、Na~+K~+、Mg~(2+)及 H_2O 含量的变化,以及高渗甘露醇对缺血后功能低下心肌的影响。实验发现:(1)缺血/再灌注后心肌组织中 Ca~(2+),H_2O 的含量与非缺血组相比分别增加42%(P<0.01)及7.6%(P0.05)。(2)于再灌注同时给予12%高渗甘露醇可明显改善缺血后心室功能:再灌注40min 时,心率-左室压乘积恢复达缺血前的85%,而不给甘露醇仅恢复66.3%(p<0.01);高渗甘露醇同时消除了缺血后功能低下心肌中 Ca~(2+)超负荷与心肌水肿,此现象提示缺血/再灌注引起的肌膜非特异性通透性改变,很可能是钙进入细胞内的路径之一。本研究结果表明,心肌 Ca~(2+)超负荷及轻度心肌水肿参与了缺血后心室功能低下,高渗甘露醇在离体大鼠心脏可明显改善缺血后功能低下心肌的功能,此作用至少部分是由于其具有减低心肌钙与水含量的效应。
The mechanism of myocardial stunning after ischemia is still unknown. In this study, we investigated the effects of Lang-cndorff method on isolated perfused rat hearts. The changes of Ca ~ (2 +), Na ~ + K ~ +, Mg ~ (2+) H 2 O content changes, as well as hypertonic mannitol on myocardial dysfunction after ischemia. The results showed that: (1) The contents of Ca ~ (2 +) and H_2O in myocardial tissue increased by 42% (P <0.01) and 7.6% ), While the content of Ca ~ (2+) increased obviously. However, the content of Na ~ +, K ~ + and Mg ~ (2+) did not change significantly (p> 0.05). (2) Simultaneous reperfusion with 12% hypertonic mannitol can significantly improve the post-ischemic ventricular function: at 40 minutes after reperfusion, the product of heart rate-left ventricular pressure restored to 85% of the pre-ischemic, but did not recover only mannitol 66.3%, respectively (p <0.01). Hypertonic mannitol also abolished Ca2 + overload and myocardial edema in the ischemic hypofunctional myocardium, suggesting that myosin nonspecific permeability caused by ischemia / reperfusion Sexual changes are probably one of the pathways for calcium to enter the cell. The results of this study show that myocardial Ca 2+ overload and mild myocardial edema are involved in post-ischemic ventricular dysfunction. Hypertonic mannitol in isolated rat heart can significantly improve myocardial function after ischemia, This effect is due at least in part to its effect of reducing the calcium and water content of the heart muscle.