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KMID : 0043320170400101135
Archives of Pharmacal Research
2017 Volume.40 No. 10 p.1135 ~ p.1145
Magnesium isoglycyrrhizinate inhibits L-type Ca2+ channels, Ca2+ transients, and contractility but not hERG K+ channels
Lin Yue

Zhang Yuan Yuan
Song Qiong Tao
Song Tao
Han Xue
Zhang Ying
Zhang Xuan
Chu Xi
Zhang Feng Hua
Chu Li
Zhang Jian Ping
Abstract
To explore the cardiovascular protective effects of Magnesium isoglycyrrhizinate (MI), especially the underlying cellular mechanisms related to L-type calcium channels and myocardial contractility, and to examine the effects of MI on hERG K+ current expressed in HEK293 cells. We used the whole-cell patch clamp technique, video-based edge detection and dual excitation fluorescence photomultiplier systems to explore the effect of MI on L-type Ca2+ currents (ICa-L) and cell contraction in rat cardiomyocytes. We also examined the rapidly activating delayed rectifier potassium current (IKr) expressed in HEK293 cells using a perforated patch clamp. MI inhibited ICa-L in a dose-dependent manner, with a half-maximal inhibitory concentration (IC50) of 0.22 mg/ml, and the maximal inhibitory effect was 61.10 ¡¾ 0.59%. MI at a concentration of 0.3 mg/ml reduced cell shortening by 24.12 ¡¾ 3.97% and the peak value of the Ca2+ transient by 36.54 ¡¾ 4.96%. MI had no significant influence on hERG K+ channels expressed in HEK293 cells at all test potentials. MI exerts protective effects on the heart via the inhibition of ICa-L and cell shortening in rat cardiomyocytes. However, MI had no significant influence on IKr; thus, MI may exert cardioprotective effects without causing drug-induced long QT syndrome.
KEYWORD
Magnesium isoglycyrrhizinate, L-type Ca2+ currents, Myocyte shortening, Ca2+ transient hERG K+ channels, Rat cardiomyocyte
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