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本工作研究了镁对模拟缺血条件(用低氧分压、无糖、高钾及高乳酸台氏液浸浴心肌)下的离体豚鼠心室肌细胞跨膜电位(TMP)和机能不应期(FRP)变化,以及在体兔心急性心肌缺血时FRP变化的影响。高镁((M~(2+))·8mmol/L)使模拟缺血豚鼠心室肌细胞静息电位(RP)、动作电位振幅(APA)及动作电位0期最大上升速度(V_(max))相对增大,动作电位时程(APD)相对延长。镁对缺血心肌FRP的变化具有双重作用,既可使过分延长的不应期相对缩短,减轻复极后不应性(PRR);又可使缩短的不应期相对延长,从而减轻了不应期离散程度。镁的上述作用对改善缺血心肌的兴奋性、传导性,减少折返激动的发生具有重要意义。
This study investigated the effects of magnesium on transmembrane potential (TMP) and dysfunction of isolated guinea pig ventricular myocytes under simulated ischemic conditions (hypoxic partial pressure, sugar-free, high-potassium, (FRP) changes and the changes of FRP in acute myocardial ischemia in rabbits. The resting potential (RP), the amplitude of action potential (APA) and the maximal rate of rise of action potential 0 (V max) in simulated ischemia guinea pig ventricular myocytes were determined by high magnesium (M ~ (2 +)) ) Relative increase, the action potential duration (APD) is relatively extended. Magnesium has a dual role in the changes of FRP in ischemic myocardium, which can not only shorten the excessive prolongation of refractory period and reduce the post-repolarization refractory (PRR), but also shorten the refractory period and thus reduce Degree of dispersion. The above effects of magnesium on the improvement of ischemic myocardium excitability, conductivity, reduce the occurrence of reentry activation is of great significance.