未成熟人心房肌细胞瞬时外向钾电流和内向整流钾电流的特性

Properties of transient outward potassium current and inward rectifier potassium current in immature human atrial myocytes.

作者信息

Liang Y, Sun X M, Wang X L

机构信息

Department of Pharmacology, Institute of Materia Medica, Beijing 100050, China.

出版信息

Zhongguo Yao Li Xue Bao. 1999 Nov;20(11):1005-10.

PMID:11270965

Abstract

AIM

To study the properties of transient outward K+ current (Ito) and inward rectifier K+ current (IKl) in immature human heart.

METHODS

Ito and IKl were recorded using whole-cell patch-clamp technique in atrial myocytes isolated from 12 immature (aged from 6 months to 5 a) human hearts.

RESULTS

Ito was voltage-dependent, activated and inactivated rapidly. The IC50 (95% confidence limits) of 4-AP on Ito was 0.64 (0.48-0.87) mmol.L-1. 4-AP 1 mmol.L-1 shifted V1/2 of activation from (6.6 +/- 2.0) mV to (19.8 +/- 3.0) mV (n = 4-10, P < 0.01). 4-AP 0.3 mmol.L-1 changed V1/2 of inactivation from (-49 +/- 4) mV to (-61.4 +/- 2.1) mV (n = 3, P < 0.01), but there were no obvious influence on voltage-dependent activation of Ito (P > 0.05). At the same concentration, the recovery time constant (tau value) was prolonged from (108 +/- 16) ms to (220 +/- 67) ms (n = 3-12, P < 0.01). IKl was also voltage-dependent. Its reverse potential was -40 mV.

CONCLUSION

Both Ito and IKl are important K+ channel currents in immature human atrial myocytes. 4-AP can affect the inactivation and recovery of Ito at low concentration (0.3 mmol.L-1) and affect its activation at high concentration (1 mmol.L-1).

摘要

目的

研究未成熟人心肌瞬时外向钾电流（Ito）和内向整流钾电流（IKl）的特性。

方法

采用全细胞膜片钳技术记录从12例未成熟（年龄6个月至5岁）人心脏分离的心房肌细胞中的Ito和IKl。

结果

Ito呈电压依赖性，激活和失活迅速。4-氨基吡啶（4-AP）对Ito的半数抑制浓度（IC50，95%置信区间）为0.64（0.48 - 0.87）mmol·L-1。1 mmol·L-1的4-AP使激活的半数电压（V1/2）从（6.6±2.0）mV移至（19.8±3.0）mV（n = 4 - 10，P < 0.01）。0.3 mmol·L-1的4-AP使失活的V1/2从（-49±4）mV变为（-61.4±2.1）mV（n = 3，P < 0.01），但对Ito的电压依赖性激活无明显影响（P > 0.05）。在相同浓度下，恢复时间常数（τ值）从（108±16）ms延长至（220±67）ms（n = 3 - 12，P < 0.01）。IKl也呈电压依赖性。其反转电位为 - 40 mV。