Membrane stretch-induced activation of a TRPM4-like nonselective cation channel in cerebral artery myocytes
Membrane stretch-induced activation of a TRPM4-like nonselective cation channel in cerebral artery myocytes
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DOI：
10.1254/jphs.fp0061332
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发表时间：
2007-04-01
影响因子：
3.5
通讯作者：
Brayden, Joseph E.
中科院分区：
文献类型：
--
作者：
Morita, Hiromitsu;Honda, Akira;Brayden, Joseph E.
已在许多类型的平滑肌细胞中观察到牵张激活阳离子通道（SAC）。然而，SAC的分子身份和激活机制仍然知之甚少。我们报告TRPM4样阳离子通道被激活的大鼠脑动脉肌细胞（CAMs）的膜拉伸。负压（>= 20 mmHg，细胞附着模式）激活分离CAM中的单通道（约20 pS）。这些通道可渗透Na+和Cs+，并被Gd 3+（30 μ M）和DIDS（100 μ M）抑制。通过膜切除消除了负压的作用，但是随后将Ca2+（>100 nM）施加到膜的细胞内侧恢复了与SAC难以区分的单通道活性。咖啡因（5 mM），消耗SR钙库，首先激活，然后废除SAC。丁卡因（100 μ M），ryanodine受体拮抗剂，抑制SAC。在HEK293细胞中过表达hTRPM4B导致阳离子通道的出现，所述阳离子通道被负压和Ca 2+激活，并且与CAM中的SAC相比具有非常相似的生物物理和药理学性质。这些研究表明，CAM中的TRPM4样通道可以通过膜拉伸激活，可能通过ryanodine受体激活，这可能有助于机械刺激后完整脑动脉的去极化和伴随的血管收缩。
Stretch-activated cation channels (SACs) have been observed in many types of smooth muscle cells. However, the molecular identity and activation mechanisms of SACs remain poorly understood. We report that TRPM4-like cation channels are activated by membrane stretch in rat cerebral artery myocytes (CAMs). Negative pressure (>= 20 mmHg, cell-attached mode) activated single channels (approximately 20 pS) in isolated CAMs. These channels were permeable to Na+ and Cs+ and inhibited by Gd3+ (30 mu M) and DIDS (100 mu M). The effect of negative pressure was abolished by membrane excision, but subsequent application of Ca2+ (>100 nM) to the intracellular side of the membrane restored single channel activity that was indistinguishable from SACs. Caffeine (5 mM), which depletes SR Ca2+-stores, first activated and then abolished SACs. Tetracaine (100 mu M), a ryanodine receptor antagonist, inhibited SACs. Overexpression of hTRPM4B in HEK293 cells resulted in the appearance of cation channels that were activated by both negative pressure and Ca2+ and which had very similar biophysical and pharmacological properties as compared with SACs in CAMs. These studies indicate that TRPM4-like channels in CAMs can be activated by membrane stretch, possibly through ryanodine receptor activation, and this may contribute to the depolarization and concomitant vasoconstriction of intact cerebral arteries following mechanical stimulation.