EFFECTS OF VASOPRESSIN AND CAMP ON SINGLE AMILORIDE-BLOCKABLE NA CHANNELS
EFFECTS OF VASOPRESSIN AND CAMP ON SINGLE AMILORIDE-BLOCKABLE NA CHANNELS
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DOI：
10.1152/ajpcell.1991.260.5.c1071
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发表时间：
1991-05-01
影响因子：
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通讯作者：
EATON, DC
中科院分区：
文献类型：
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作者：
MARUNAKA, Y;EATON, DC
为了确定抗利尿激素在钠转运紧密上皮中增加钠转运的机制，我们在精氨酸抗利尿激素治疗前后，在培养的远端肾细胞（A6）的膜斑块中检测了单阿米洛利可阻断的钠通道。抗利尿激素（40 mU/ml）预处理细胞40-50分钟可增加NP(o) （N， Na通道数量；P(o)，单个Na通道打开概率）。NP(o)的增加是由于导电Na通道数量的增加，而单个Na通道的打开概率很少或没有变化。用1 mM N6,2′- o -二丁基腺苷3′，5′-环单磷酸（DBcAMP）预处理细胞1 h也可提高NP(0)。DBcAMP预处理引起的NP(o)的增加也是由于导电Na通道数量的增加，而单个Na通道的打开概率没有变化。用霍乱毒素（CTX; 250 ng/ml）预处理4小时的细胞与用加压素或DBcAMP处理的细胞相似；也就是说，每个贴片的Na通道数量增加，对单个Na通道的打开概率影响很小或没有影响。对于来自许多未经处理的细胞的斑块，当发生频率与单个斑块中的通道数绘制时，直方图由单个峰值组成，每个斑块的通道数为2.0 +/- 1.5 （+/- SD， 126个斑块）。后叶加压素、DBcAMP或CTX预处理细胞后，同一直方图包含两个峰，后叶加压素分别为1.8 +/- 1.2和9.2 +/- 1.5 （+/- SD，分别为38和53个patch）。这些观察结果表明，用抗利尿激素、DBcAMP或CTX预处理细胞可能通过促进新钠通道簇的插入而起作用。
To determine the mechanism by which vasopressin increases sodium transport in soidum-transporting, tight epithelia, we examined single amiloride-blockable Na channels in membrane patches from cultured distal nephron cells (A6) either before or after treatment with arginine vasopressin. Pretreatment of cells with vasopressin (40 mU/ml) for 40-50 min increases NP(o) (N, the number of Na channels; P(o), the open probability of an individual Na channel). The increase in NP(o) is due to an increase in the number of conductive Na channels with little or no change in the open probability of individual Na channels. Pretreatment of cells for 1 h with 1 mM N6,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (DBcAMP) also increased NP(o). The increase in NP(o) caused by DBcAMP pretreatment is also due to the increase in the number of conductive Na channels with no change in the open probability of individual Na channels. Cells pretreated with cholera toxin (CTX; 250 ng/ml) for 4 h appeared similar to cells that had been treated with vasopressin or DBcAMP; that is, the number of Na channels per patch increased with little or no effect on the open probability of individual Na channels. For patches from many untreated cells, when the frequency of occurrence is plotted against the number of channels in an individual patch, the histogram consists of a single peak with a number of channels per patch of 2.0 +/- 1.5 (+/- SD, 126 patches). After pretreatment of cells with vasopressin, DBcAMP, or CTX, the same histogram contains two peaks after vasopressin of 1.8 +/- 1.2 and 9.2 +/- 1.5 (+/- SD, 38 and 53 patches, respectively). These observations suggest that pretreatment of cells with vasopressin, DBcAMP, or CTX may act by promoting insertion of clusters of new sodium channels.