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目的 :研究不同时期胚胎心肌细胞超极化激活的电流 (hyperpo larization activatedcurrent,If)和L 型钙电流 (L typecalciumcurrent,ICa L)表达的发育依赖性变化。方法 :运用全细胞膜片钳技术 ,记录不同发育阶段胚胎心肌细胞的If 和ICa L。结果 :If 通道在早期(EDS)、中期 (IDS)、晚期 (LDS)胚胎心室肌细胞上的功能性表达水平分别为 85 .70 %、71.60 %、44 .40 % ;其电流密度分别是 -7.2 4±1.2 8pApF- 1 、-6.48± 0 .99pApF- 1 、-3 .76± 1.0 4pApF- 1 (P均<0 .0 1)。If 通道在中、晚期胚胎心房肌细胞上的功能性表达水平分别为 77%、48.3 0 % (P <0 .0 1) ;其电流密度分别是 -8.86± 2 .3 4pApF- 1 与 -4 .62± 1.0 6pApF- 1 (P <0 .0 1)。早、中、晚期胚胎心肌细胞的ICa L的功能表达变化不明显 (P >0 .0 5 )。结论 :胚胎心肌细胞的If的功能表达呈发育依赖性下降 ,ICa L的功能表达没有发育依赖性改变
Objective: To investigate the developmental changes of hyperpolarization activated current (If) and L tyrosine calcium current (ICa L) in embryonic cardiomyocytes at different stages. Methods: The whole cell patch clamp technique was used to record the If and ICa L of embryonic cardiomyocytes at different developmental stages. RESULTS: The functional expression levels of If channels were 85.7%, 71.60%, 44.40% in embryonic ventricular myocytes of early stage (EDS), mid stage (IDS) and late stage (LDS) respectively. The current density of If channel was - 7.2 4 ± 1.2 8pApF-1, -6.48 ± 0.99pApF-1, -3.76 ± 1.0 4pApF-1 (P <0.01). The functional expression of If channel in middle and late embryonic atrial myocytes was 77% and 48.3%, respectively (P <0.01). The current density of If channel was -8.86 ± 2.34 and the expression of -4pApF-1 and -4 .62 ± 1.0 6 pApF-1 (P <0.01). The functional expression of ICa L in early, middle and late embryonic cardiomyocytes did not change significantly (P> 0.05). CONCLUSION: The functional expression of If in embryonic cardiomyocytes is developmentally dependent, and the functional expression of ICa L is not developmentally dependent