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低镁和缺镁对离体豚鼠右心室肌单细胞动作电位的效应

陈万春, 周琦, 王恒润, 陈革, 汤昱, 蒲勤宪, 王正山, 梁子钧

上海市第六人民医院内科. 上海；上海第一医学院生物物理系. 上海

摘要

取豚鼠右心室肌,在改良 Krebs 溶液灌注下,用微电极记录动作电位(AP)12只豚鼠72次心肌单细胞 AP 有关参数的平均值为:静息电位(RP)-76±9mV;动作电位振幅(APA)107±7mV;动作电位时程(APD)_(-30mV)为254±123ms;APD_(100)为312±133ms。当灌注液中镁离子浓度减低到0.6mol/L 时,72次 AP 的 APD_(-30mV)和APD_(100)分別为对照值的80.7%和83%;在无镁溶液中,改变更为显著,分别为对照值的70.9%和76.7%;RP 和 APA 则变化均不大。实验提示:低镁可使 APD 缩短,从而可能影响体表心电图 T 波的第3位相;此外,APD 的缩短意味着不应期相对缩短,这或许是低镁症时出现室性早搏的因素。

关键词： 镁离子; 动作电位; 动作电位时程

Effects of low magnesium and magnesium-free solutions on action potential of isolated right ventricular muscle cell in tide guinea pig

Chen Wanchun, Zhou Qi, Wang Hengrun, Chen Ge, Tang Yu, Pu Qinxian, Wang Zhengshan, Liang Zijun

Shanghai Sixth People's Hospital. Shanghai, China；Department of Biophysics, Shanghai First Medical College. Shanghai, China

Abstract

Action potentials (AP) of single cells in guinea pig's isolated right ventricular muscle strips perfused with a modified Krebs solution were recorded with microelectrodes. Relevant normal values were as follows: resting potential (RP)，-76±9 mV; action potential amplitude (APA), 107±7mV; action potential duration -30ms (APD_(30mV)), 254±123 ms; action potential duration 100. (APD_(100)), 321±133ms. These indices were taken from 72 AP records from 12 guinea pigs. When the concentration of the magnesium ion in the perfusate was reduced to 0.6 mmol/L, the average values of APD_(-30mV) and APD_(100) decreased to 80.7 and 83% respectively of the control. When magnesium ion was deprived, this de crease became more marked, being 70.9 % and 76.7 % of the control values. However RP and APA showed no significant change. The result demonstrates that low or no magnesium ion in the perfusate shortens APD and thus may affect phase 3 of the AP. This may explain the T wave changes in the ECG in clinical hypomagnesemia. The shortening of the effective refractory period may be a factor in the appearance of permature beats.

Key words: Magnesium ion;Action potential;Action potential duration

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引用本文：

陈万春, 周琦, 王恒润, 陈革, 汤昱, 蒲勤宪, 王正山, 梁子钧. 低镁和缺镁对离体豚鼠右心室肌单细胞动作电位的效应[J]. 生理学报 1985; 37 (1): .

Chen Wanchun, Zhou Qi, Wang Hengrun, Chen Ge, Tang Yu, Pu Qinxian, Wang Zhengshan, Liang Zijun. Effects of low magnesium and magnesium-free solutions on action potential of isolated right ventricular muscle cell in tide guinea pig. Acta Physiol Sin 1985; 37 (1): (in Chinese with English abstract).