Electrical properties of isolated rat adrenal glomerulosa and fasciculata cells.
Electrical properties of isolated rat adrenal glomerulosa and fasciculata cells.
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DOI：
10.1210/endo-120-3-903
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发表时间：
1987-03
期刊：
影响因子：
4.8
通讯作者：
S. Quinn;M. Cornwall;G. Williams
中科院分区：
文献类型：
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作者：
S. Quinn;M. Cornwall;G. Williams
用细胞内电压记录法和恒流刺激法研究了大鼠肾上腺小球和束状细胞的被动和主动电特性。肾小球细胞和束状细胞的平均静息膜电位分别为-78.9+/-4.2 mV和-77.8+/-5.0 mV。膜电位对外源K+浓度变化的响应在28 mM以下是稳定和可逆的，且不受外源Cl-的影响。膜电位与外源K+浓度的对数在4~28 mm之间呈线性关系，膜电位可用恒定电场方程的简化形式来预测，肾小球细胞的[K]i为138.5 mm，pNA/pk为0.015，束状细胞的[K]i为112.4 mm，pNA/pk为0.011。在电流钳制条件下，两种电池的去极化电流阶跃的膜电压与外加电流之间呈现非线性关系。去极化电流脉冲引发再生响应，紧随其后的是整流稳态电位。在静息膜电位以下，超极化使再生反应的最大上升速率和峰值增大，去极化使再生反应的最大上升速率和峰值降低。再生反应不受Na+去除的影响。升高的钙离子浓度增加了再生反应的上升速率、峰值幅度和下降速率，但缩短了再生反应的持续时间。用Sr2+或Ba2+取代Ca2+可维持再生反应，但可被Mn2+或Co2+抑制。在肾小球和束状细胞中诱导的再生反应具有相似的特征。这些结果表明，再生反应背后的离子机制是电压依赖性的钙电导。肾上腺小球和束状细胞表现出与其他可兴奋细胞相同的电特性。就膜电位而言，它们是很好的K+传感器，接近对K+完全透过膜的最高灵敏度。此外，在肾上腺小球和束状细胞中都发现了钙离子再生反应，这种反应可能参与类固醇激素分泌刺激。
Passive and active electrical properties of isolated rat adrenal glomerulosa and fasciculata cells were studied by intracellular voltage-recording and constant current stimulation. The average resting membrane potential was -78.9 +/- 4.2 mV for glomerulosa cells and -77.8 +/- 5.0 mV for fasciculata cells. The response of the membrane potential to changes in external K+ concentration was stable and reversible for changes up to 28 mM and was independent of external Cl-. The relationship between membrane potential and the log of external K+ concentration was linear between 4 and 28 mM, and the membrane potential could be predicted by a simplified form of the constant field equation with a [K]i of 138.5 mM and a PNa/PK of 0.015 for glomerulosa cells and a [K]i of 112.4 mM and a PNa/PK of 0.011 for fasciculata cells. Under current clamp conditions, both cells demonstrated a nonlinear relationship between membrane voltage and applied current for depolarizing current steps. Depolarizing current pulses elicited a regenerative response and were followed by a rectifying steady state potential. The maximum rate of rise and the peak amplitude of the regenerative response were increased by prior hyperpolarization below the resting membrane potential and decreased by depolarization. The regenerative response was unaffected by the removal of Na+. Elevated Ca2+ concentrations increased the rate of rise, peak amplitude, and rate of fall, but decreased the duration of the regenerative response. The regenerative response was maintained upon replacement of Ca2+ with Sr2+ or Ba2+, but was inhibited by Mn2+ or Co2+. Regenerative responses elicited in both glomerulosa and fasciculata cells exhibited similar characteristics. The results suggest the ionic mechanism underlying the regenerative response to be a voltage-dependent Ca2+ conductance. Both adrenal glomerulosa and fasciculata cells demonstrate electrical properties in common with other excitable cells. They are good K+ sensors with regard to their membrane potential, approaching the maximum sensitivity expected for a membrane exclusively permeable to K+. In addition, the Ca2+ regenerative response, which has been identified in both adrenal glomerulosa and fasciculata cells, may be involved in secretagogue stimulation of steroidogenesis.