TTX-sensitive voltage-gated Na+ channels are expressed in mesenteric artery smooth muscle cells
TTX-sensitive voltage-gated Na+ channels are expressed in mesenteric artery smooth muscle cells
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DOI：
10.1152/ajpheart.01156.2004
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发表时间：
2005-07-01
影响因子：
4.8
通讯作者：
Matteson, DR
中科院分区：
文献类型：
--
作者：
Berra-Romani, R;Blaunstein, MP;Matteson, DR
用全细胞膜片钳技术研究了肠系膜动脉平滑肌细胞（SMCs）电压门控性Na+通道的存在及其特性。使用两种具有不同酶组合的解离方案酶促解离来自小鼠和大鼠肠系膜动脉的SMC。用胶原酶和弹性蛋白酶分离的心肌细胞中存在Na+和Ca 2+通道电流。与此相反，Na+电流没有检测到，但钙电流存在于木瓜蛋白酶和胶原酶分离的细胞。硝苯地平可阻断Ca 2+电流。Na+电流对硝苯地平不敏感，对细胞外Na+浓度的变化敏感，并被河豚毒素阻断，IC 50为4.3 nM。Na+电导在-16 mV时达到最大激活的一半，稳态失活在-53 mV时达到最大失活的一半。这些值与各种SMC类型中报告的值相似。在1 μ M的蛙毒素的存在下，Na+的电导-电压关系被移动了27 mV的超极化方向，失活几乎完全消除，失活率降低。本研究表明，大鼠和小鼠肠系膜动脉SMC中存在TTX敏感的电压门控Na+通道。这些通道在新鲜分离的SMC中的存在严重依赖于酶促解离条件。这可能解决关于动脉平滑肌中存在Na+通道的争议。
The presence and properties of voltage-gated Na+ channels in mesenteric artery smooth muscle cells (SMCs) were studied using whole cell patch-clamp recording. SMCs from mouse and rat mesenteric arteries were enzymatically dissociated using two dissociation protocols with different enzyme combinations. Na+ and Ca2+ channel currents were present in myocytes isolated with collagenase and elastase. In contrast, Na+ currents were not detected, but Ca2+ currents were present in cells isolated with papain and collagenase. Ca2+ currents were blocked by nifedipine. The Na+ current was insensitive to nifedipine, sensitive to changes in the extracellular Na+ concentration, and blocked by tetrodotoxin with an IC50 at 4.3 nM. The Na+ conductance was half maximally activated at -16 mV, and steady-state inactivation was half-maximal at -53 mV. These values are similar to those reported in various SMC types. In the presence of 1 mu M batrachotoxin, the Na+ conductance-voltage relationship was shifted by 27 mV in the hyperpolarizing direction, inactivation was almost completely eliminated, and the deactivation rate was decreased. The present study indicates that TTX-sensitive, voltage-gated Na+ channels are present in SMCs from the rat and mouse mesenteric artery. The presence of these channels in freshly isolated SMC depends critically on the enzymatic dissociation conditions. This could resolve controversy about the presence of Na+ channels in arterial smooth muscle.