Voltage-gated sodium channels in cardiac microvascular endothelial cells.
Voltage-gated sodium channels in cardiac microvascular endothelial cells.
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心脏微血管内皮细胞中的电压门控钠通道。
DOI：
10.1152/ajpheart.1998.274.2.h506
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Fan,J
中科院分区：
文献类型：
--
作者：
Walsh,KB;Wolf,MB;Fan,J
本研究的目的是确定是否内向钠或钙电流可以测量心脏微血管内皮细胞（CMEC）。从大鼠心室肌中分离CMEC，并在培养的第1- 4天进行研究。荧光标记的乙酰化低密度脂蛋白（LDL）的差异摄取表明，原代培养物含有>90%的CMEC。膜电流测量与使用的全细胞排列的膜片钳技术与Cs+内部解决方案，以防止污染外向K+电流。电压阶跃正至−30 mV导致快速内向Na+电流（INa）激活。在检测的20个细胞中，0 mV时测得的峰值内向电流为2.1 pA/pF。INA失活所需的半最大电压为−45 mV，失活后电流恢复时间常数为10 ms。用N-甲基葡萄糖胺替代外源钠可消除内向电流，河豚毒素（TTX）（解离常数= 5 nM）和石房蛤毒素（50 nM）。通过应用佛波醇12，13-二丁酸酯刺激蛋白激酶C，导致INa的振幅增加，而电流激活的电压依赖性没有任何变化。因此，心脏微血管的内皮可能是唯一的表达电压门控，TTX敏感的Na+通道。
The goal of this study was to determine whether inward Na+or Ca2+currents could be measured in cardiac microvascular endothelial cells (CMEC). CMEC were isolated from rat ventricular muscle and studied duringdays 1–4in culture. Differential uptake of fluorescently labeled acetylated low-density lipoproteins (LDL) indicated that the primary culture contained >90% CMEC. Membrane currents were measured with the use of the whole cell arrangement of the patch-clamp technique with a Cs+internal solution to prevent contamination by outward K+currents. Voltage steps positive to −30 mV resulted in the activation of a fast, inward Na+current (INa). In 20 cells examined, the peak inward current measured at 0 mV was 2.1 pA/pF. The half-maximal voltage required for inactivation ofINawas −45 mV, and the current recovered from inactivation with a time constant of 10 ms. Inward currents were eliminated by replacement of external sodium withN-methylglucamine and were blocked by both tetrodotoxin (TTX) (dissociation constant = 5 nM) and saxitoxin (50 nM). Stimulation of protein kinase C, through application of phorbol 12,13-dibutyrate, resulted in an increase in the amplitude ofINawithout any change in the voltage dependence of current activation. Thus the endothelium of cardiac microvessels may be unique in expressing voltage gated, TTX-sensitive Na+channels.