GESTATIONAL CHANGE IN NA+ AND CA-2+ CHANNEL CURRENT DENSITIES IN RAT MYOMETRIAL SMOOTH-MUSCLE CELLS
GESTATIONAL CHANGE IN NA+ AND CA-2+ CHANNEL CURRENT DENSITIES IN RAT MYOMETRIAL SMOOTH-MUSCLE CELLS
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DOI：
10.1152/ajpcell.1991.260.3.c658
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发表时间：
1991-03-01
影响因子：
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通讯作者：
SPERELAKIS, N
中科院分区：
文献类型：
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作者：
INOUE, Y;SPERELAKIS, N
采用全细胞电压钳法，对从妊娠大鼠子宫纵层新鲜分离的单个平滑肌细胞，研究了妊娠期间Na+和Ca2+通道电流的变化。 Na+ 和 Ca2+ 电流的电流-电压关系在妊娠期间没有变化。 阈值电压、峰值内向电流处的电压和反转电势（外推）实际上是相同的。 Ca2+通道的平均电流密度在第9天和第21天之间几乎没有变化；第 5 天的该值稍低。 相比之下，妊娠期间子宫肌层中快速Na+通道的平均电流密度显着增加：从第5天的0到第9天的0.19 +/- 0.16，到第14天的0.56 +/- 0.13，到第18天的0.90 +/- 0.13，到第21天的0.86 +/- 0.14 pA/pF。这几乎由于拥有快速 Na+ 通道的细胞比例增加，妊娠期间快速 Na+ 通道的平均密度呈线性增加。 这些结果表明，随着足月的临近，快速 Na+ 通道在子宫肌层活动中的作用变得越来越重要。 我们认为快速的 Na+ 电流可能与激发的传播有关。
The change of Na+ and Ca2+ channel currents during gestation was investigated using the whole cell voltage-clamp method on single smooth muscle cells freshly isolated from the longitudinal layer of pregnant rat uterus. The current-voltage relationships for both the Na+ and Ca2+ currents did not change during gestation. The threshold voltage, the voltage at the peak inward current, and the reversal potential (extrapolated) were virtually identical. The averaged current densities of Ca2+ channel were almost unchanged between days 9 and 21; this value at day 5 was somewhat lower. In contrast, the averaged current density of fast Na+ channels increased markedly in the myometrium during gestation: from 0 at day 5 to 0.19 +/- 0.16 at day 9, to 0.56 +/- 0.13 at day 14, to 0.90 +/- 0.13 at day 18, and to 0.86 +/- 0.14 pA/pF at day 21. This almost linear increase in the averaged density of fast Na+ channels during gestation occurs because of an increase in the fraction of cells which possessed fast Na+ channels. These results suggest that the role of fast Na+ channels in myometrial activity becomes more and more important as term approaches. We suggest that the fast Na+ current may be involved in spread of excitation.