本文旨在研究细胞内高镁对离体豚鼠心室肌细胞L-型钙通道的单通道门控特性的影响。急性酶消化法分离豚鼠心室肌细胞,应用膜片钳膜内向外单通道记录模式观察不同浓度细胞内镁([Mg2+]i)对心肌细胞L-型钙通道单通道电流的影响。结果显示,对照组([Mg2+]i 0.9 mmol/L)的心肌细胞L-型钙通道相对活性为(176.5±34.1)%,而高镁组([Mg2+]i 8.1 mmol/L)钙通道相对活性显著降低至(64.8±18.1)%(P<0.05)。另外,8.1 mmol/L[Mg2+]i使心肌细胞L-型钙通道的平均开放时间缩短至对照组的约25%(P<0.05),但对通道平均关闭时间无明显影响。以上结果提示,细胞内高镁主要通过缩短通道平均开放时间抑制豚鼠心室肌细胞L-型钙通道的活性。 The aim of this study was to investigate the effect of intracellular high magnesium on single-channel gating of isolated L-type calcium channels in isolated guinea pig ventricular myocytes. Acute enzymatic digestion was used to separate guinea pig ventricular myocytes. The effects of magnesium ([Mg2 +] i) in different concentration on L-type calcium channels single-channel current were observed by single-channel patch-clamp recording. The results showed that the relative activity of L-type calcium channel in control group ([Mg2 +] i 0.9 mmol / L) was (176.5 ± 34.1)%, while the calcium channel in high Mg group Activity was significantly reduced to (64.8 ± 18.1)% (P <0.05). In addition, 8.1 mmol / L [Mg2 +] i reduced the average open time of L-type calcium channels in cardiomyocytes to about 25% of the control group (P <0.05), but had no significant effect on the mean channel closure time. The above results suggest that intracellular high magnesium inhibits the L-type calcium channel activity of guinea pig ventricular myocytes primarily by shortening the mean channel opening time.