PROPERTIES OF LARGE-CONDUCTANCE K+-CHANNELS IN HUMAN MYOMETRIUM DURING PREGNANCY AND LABOR
PROPERTIES OF LARGE-CONDUCTANCE K+-CHANNELS IN HUMAN MYOMETRIUM DURING PREGNANCY AND LABOR
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DOI：
10.1098/rspb.1993.0002
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发表时间：
1993-01-22
影响因子：
4.7
通讯作者：
ASHFORD, MLJ
中科院分区：
文献类型：
--
作者：
KHAN, RN;SMITH, SK;ASHFORD, MLJ
妊娠子宫在足月时由电静默状态转变为高度兴奋状态是一个引人注目的生理事件，人们对此知之甚少。在这里，我们提供了第一个描述，从单通道记录，一个大电导（212 pS）钙激活钾通道（BK（Ca））在人类妊娠子宫肌层，在劳动组织，是不存在或已大大改变其生理和药理学特性。在后者中，K+通道具有与BK（Ca）通道相同的电导（221 pS）和K+选择性，但不表现出Ca 2+或电压敏感性。我们把这些通道称为BK通道。此外，来自妊娠组织的BK（Ca）通道的活性被内施用Ba 2+而不是四乙基铵（TEA）抑制，而BK通道的活性对内施用TEA而不是Ba 2+敏感。BK（Ca）通道的作用可能是在妊娠期间抑制子宫肌层活动，而BK通道活性可能在提供Ca2+非依赖性K+电导方面很重要，这将允许细胞质Ca2+水平升高，而不会激活通常由BK（Ca）通道提供的反作用Ca2+依赖性外向电流，BK（Ca）通道本质上倾向于对抗去极化。研究结果表明，K+通道可能在决定子宫肌层的功能活动中起重要作用。
The conversion of the electrically silent pregnant uterus to highly excitable at term represents a dramatic physiological event which is poorly understood. Here we provide the first description, from single-channel recordings, of a large conductance (212 pS) calcium-activated potassium channel (BK(Ca)) in human pregnant myometrium which, in labour tissue, is either absent or has been considerably altered in its physiological and pharmacological properties. In the latter, the K+ channels have an identical conductance (221 pS) and K+ selectivity to BK(Ca) channels but exhibit no Ca2+ or voltage sensitivity. We have termed these BK channels. Furthermore, the activity of the BK(Ca) channel from pregnant tissue is, inhibited by internal application of Ba2+ but not tetraethylammonium (TEA), whereas the activity of the BK channel is sensitive to internal TEA but not Ba2+. The role of the BK(Ca) channel may be to suppress myometrial activity during gestation whereas BK channel activity may be important in providing a Ca2+-independent K+ conductance which would allow cytoplasmic Ca2+ levels to rise without activating a counteracting Ca2+-dependent outward current, normally provided by the BK(Ca) channels which, by its very nature, would tend to oppose depolarization. The findings suggest that K+ channels may have an important role in determining the functional activity of the myometrium.