蛋白激酶C对慢性缺氧大鼠肺动脉平滑肌细胞电压门控钾通道的影响。

The effect of protein kinase C on voltage-gated potassium channel in pulmonary artery smooth muscle cells from rats exposed to chronic hypoxia.

作者信息

Zhang Yong-chang, Ni Wang, Zhang Zhen-kiang, Xu Yong-jian

机构信息

Department of Respiratory Disease, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, China.

出版信息

Chin Med J (Engl). 2004 Jan;117(1):19-23.

PMID:14733767

Abstract

BACKGROUND

Chronic hypoxia can cause pulmonary hypertension and pulmonary heart disease with high mortality. The signal transduction pathway of protein kinase C (PKC) plays an important role in chronic pulmonary hypertension. So it is necessary to investigate the effect of PKC on voltage-gated potassium (K+) channels in pulmonary artery smooth muscle cells of rats exposed to chronic hypoxia.

METHODS

Male Wistar rats were randomly divided into a control group (group A) and a chronic hypoxia group (group B). Group B received hypoxia [oxygen concentration (10 +/- 1)%] eight hours per day for four consecutive weeks. Single pulmonary artery smooth muscle cells were obtained using an acute enzyme separation method. Conventional whole cell patch clamp technique was used to record resting membrane potential, membrane capacitance and voltage-gated K+ currents. The changes in voltage-gated K+ currents before and after applying paramethoxyamphetamine (PMA) (500 nmol/L), an agonist of PKC, and PMA plus carbohydrate mixture of glucose, fructose and xylitol (GFX) (30 nmol/L), an inhibitor of PKC, were compared between the two groups.

RESULTS

The resting membrane potential in group B was significantly lower than that of group A: -(29.0 +/- 4.8) mV (n = 18) vs -(42.5 +/- 4.6) mV (n = 35) (P < 0.01). But there was no change in membrane capacitance between the two groups: (17.9 +/- 4.6) pF (n = 40) vs (19.7 +/- 5.8) pF (n = 31) (P > 0.05). The voltage-gated K+ currents were significantly inhibited by PMA in group A, and this effect was reversed by GFX. However, the voltage-gated K+ currents in group B were not affected by PMA.

CONCLUSIONS

The resting membrane potential and voltage-gated K+ currents in pulmonary artery smooth muscle cells from rats exposed to chronic hypoxia decreased significantly. It seems that PKC has different effects on the voltage-gated K+ currents of pulmonary artery smooth muscle cells under different conditions.

摘要

背景

慢性缺氧可导致肺动脉高压和肺心病，死亡率很高。蛋白激酶C（PKC）信号转导通路在慢性肺动脉高压中起重要作用。因此，有必要研究PKC对慢性缺氧大鼠肺动脉平滑肌细胞电压门控钾（K+）通道的影响。

方法

将雄性Wistar大鼠随机分为对照组（A组）和慢性缺氧组（B组）。B组连续4周每天接受8小时缺氧[氧浓度（10±1）%]。采用急性酶分离法获得单个肺动脉平滑肌细胞。使用传统的全细胞膜片钳技术记录静息膜电位、膜电容和电压门控K+电流。比较两组在应用PKC激动剂对甲氧基苯丙胺（PMA）（500 nmol/L）以及PKC抑制剂PMA加葡萄糖、果糖和木糖醇碳水化合物混合物（GFX）（30 nmol/L）前后电压门控K+电流的变化。

结果

B组的静息膜电位显著低于A组：-（29.0±4.8）mV（n = 18）对-（42.5±4.6）mV（n = 35）（P < 0.01）。但两组之间的膜电容没有变化：（17.9±4.6）pF（n = 40）对（19.7±5.8）pF（n = 31）（P > 0.05）。A组中PMA显著抑制电压门控K+电流，GFX可逆转此效应。然而，B组中的电压门控K+电流不受PMA影响。