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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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Citing This Article：

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).