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首页> 外文期刊>American Journal of Physiology >A cationic nonselective stretch-activated channel in the Reissner's membrane of the guinea pig cochlea.
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A cationic nonselective stretch-activated channel in the Reissner's membrane of the guinea pig cochlea.

机译：豚鼠耳蜗Reissner膜中的阳离子非选择性拉伸激活通道。

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摘要

The Reissner's membrane (RM) separates in the mammalian cochlea the K(+)-rich endolymph from the Na(+)-rich perilymph. The patch-clamp technique was used to investigate the transport mechanisms in epithelial cells of RM freshly dissected from the guinea pig cochlea. This study shows a stretch-activated nonselective cationic channel (SA channel) with a linear current-voltage relationship (23 pS) highly selective for cations over anions [K+ approximately Na+ (1) > Ba2+ (0.65) > Ca2+ (0.32) Cl- (0.14)] and activated by the intrapipette gradient pressure. The open probability-pressure relationship is best fitted by a Boltzmann distribution (half-maximal pressure = 37.8 mmHg, slope constant = 8.2 mmHg). SA channels exhibit a strong voltage dependency and are insensitive to internal Ca2+, ATP, and fenamates but are blocked by 1 microM GdCl3 in the pipette. They are reversibly activated by in situ superfusion of the cell with hyposmotic solutions. Kinetic studies show that depolarization and mechanical or osmotic stretch modify the closed and open time constants probably by a different mechanism. These channels could participate in pressure-induced modifications of ionic permeability of the RM.
机译：Reissner的膜（RM）在哺乳动物的耳蜗中将富含K（+）的内淋巴与富含Na（+）的外淋巴分开。膜片钳技术用于研究从豚鼠耳蜗中新鲜分离出的RM在上皮细胞中的转运机制。这项研究显示了具有线性电流-电压关系（23 pS）的拉伸激活非选择性阳离子通道（SA通道），对阳离子对阴离子的阳离子具有高度选择性[K +大约Na +（1）> Ba2 +（0.65）> Ca2 +（0.32） Cl-（0.14）]，并通过移液器内的梯度压力激活。开放概率-压力关系最好通过玻尔兹曼分布来拟合（半最大压力= 37.8 mmHg，斜率常数= 8.2 mmHg）。 SA通道表现出很强的电压依赖性，并且对内部Ca2 +，ATP和虾酸盐不敏感，但被移液管中的1 microM GdCl3阻塞。通过用低渗溶液原位细胞融合可逆地激活它们。动力学研究表明，去极化和机械或渗透拉伸可能通过不同的机制改变了闭合和开放时间常数。这些通道可以参与压力诱导的RM离子渗透性的修饰。

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