High intracellular Mg2+ affects upon the activities of L-type calcium channel in guinea-pig ven-tricular myocytes

【作者】 赵美眯； 雷明； 邵冬雪； 王红梅； 封瑞； 胡慧媛； 孙雪菲； 郭凤； 赵金生； 郝丽英；

【机构】 中国医科大学药学院药物毒理教研室；

【摘要】 This study is aimed to investigate the effects of high intracellular Mg2+(Mg2+i)upon the gating-mechanism of L-type calcium channel in guinea-pig ventricular myocytes.By adopting inside-out configuration of patch clamp technique,single channel currents of the L-type calcium channel were recorded with different Mg2+i concentrations.In control group in which Mg2+i is 0.9 mmol/L,the relative activities of calcium channel were 176.5±34.1%(n=7).When Mg2+i concentration was increased from0.9 to 8.1 mmol/L,the relative activities of calcium channel decreased to 64.8±18.1%(n=6,P<0.05).Moreover,at 8.1 mmol/L Mg2+i,the mean open time of calcium channel was shortened to about 25%of that in control condition(P<0.05),but the mean close time of calcium channel was not altered.These results suggest that high Mg2+i may inhibit the channel activities,which are mainly due to the shortening of the mean open time of single L-type calcium channel.更多还原

【Abstract】 This study is aimed to investigate the effects of high intracellular Mg2+(Mg2+i) upon the gating-mechanism of L-type calcium channel in guinea-pig ventricular myocytes.By adopting inside-out configuration of patch clamp technique,single channel currents of the L-type calcium channel were recorded with different Mg2+i concentrations.In control group in which Mg2+i is 0.9 mmol/L,the relative activities of calcium channel were 176.5 ± 34.1%(n = 7).When Mg2+i concentration was increased from 0.9 to 8.1 mmol/L,the relative activities of calcium channel decreased to 64.8 ± 18.1%(n = 6,P < 0.05).Moreover,at 8.1 mmol/L Mg2+i,the mean open time of calcium channel was shortened to about 25% of that in control condition(P < 0.05),but the mean close time of calcium channel was not altered.These results suggest that high Mg2+i may inhibit the channel activities,which are mainly due to the shortening of the mean open time of single L-type calcium channel.更多还原