高渗应激增加原代培养大鼠肝细胞的钠离子电导。
Hypertonic stress increases the Na+ conductance of rat hepatocytes in primary culture.
作者信息
Wehner F, Sauer H, Kinne R K
机构信息
Max-Planck-Institut für molekular Physiologie, Abteilung Epithelphysiologie, Dortmund, Germany.
出版信息
J Gen Physiol. 1995 Apr;105(4):507-35. doi: 10.1085/jgp.105.4.507.
We studied the ionic mechanisms underlying the regulatory volume increase of rat hepatocytes in primary culture by use of confocal laser scanning microscopy, conventional and ion-sensitive microelectrodes, cable analysis, microfluorometry, and measurements of 86Rb+ uptake. Increasing osmolarity from 300 to 400 mosm/liter by addition of sucrose decreased cell volumes to 88.6% within 1 min; thereafter, cell volumes increased to 94.1% of control within 10 min, equivalent to a regulatory volume increase (RVI) by 44.5%. This RVI was paralleled by a decrease in cell input resistance and in specific cell membrane resistance to 88 and 60%, respectively. Ion substitution experiments (high K+, low Na+, low Cl-) revealed that these membrane effects are due to an increase in hepatocyte Na+ conductance. During RVI, ouabain-sensitive 86Rb+ uptake was augmented to 141% of control, and cell Na+ and cell K+ increased to 148 and 180%, respectively. The RVI, the increases in Na+ conductance and cell Na+, as well as the activation of Na+/K(+)-ATPase were completely blocked by 10(-5) mol/liter amiloride. At this concentration, amiloride had no effect on osmotically induced cell alkalinization via Na+/H+ exchange. When osmolarity was increased from 220 to 300 mosm/liter (by readdition of sucrose after a preperiod of 15 min in which the cells underwent a regulatory volume decrease, RVD) cell volumes initially decreased to 81.5%; thereafter cell volumes increased to 90.8% of control. This post-RVD-RVI of 55.0% is also mediated by an increase in Na+ conductance. We conclude that rat hepatocytes in confluent primary culture are capable of RVI as well as of post-RVD-RVI. In this system, hypertonic stress leads to a considerable increase in cell membrane Na+ conductance. In concert with conductive Na+ influx, cell K+ is then increased via activation of Na+/K(+)-ATPase. An additional role of Na+/H+ exchange in the volume regulation of rat hepatocytes remains to be defined.
我们通过共聚焦激光扫描显微镜、传统和离子敏感微电极、电缆分析、微量荧光测定法以及对⁸⁶Rb⁺摄取的测量，研究了原代培养大鼠肝细胞调节性容积增加的离子机制。通过添加蔗糖将渗透压从300 mosm/升提高到400 mosm/升，在1分钟内细胞容积降至对照的88.6%；此后，细胞容积在10分钟内增加到对照的94.1%，相当于调节性容积增加（RVI）44.5%。这种RVI伴随着细胞输入电阻和细胞膜对⁸⁶Rb⁺的比电阻分别降至88%和60%。离子替代实验（高K⁺、低Na⁺、低Cl⁻）表明，这些膜效应是由于肝细胞Na⁺电导增加所致。在RVI期间，哇巴因敏感的⁸⁶Rb⁺摄取增加到对照的141%，细胞Na⁺和细胞K⁺分别增加到148%和180%。RVI、Na⁺电导和细胞Na⁺的增加以及Na⁺/K⁺-ATP酶的激活被10⁻⁵mol/升的氨氯地平完全阻断。在此浓度下，氨氯地平对通过Na⁺/H⁺交换的渗透诱导细胞碱化没有影响。当渗透压从220 mosm/升增加到300 mosm/升（在细胞经历调节性容积减少（RVD）的15分钟预期间后重新添加蔗糖）时，细胞容积最初降至81.5%；此后细胞容积增加到对照的90.8%。这种55.0%的RVD后RVI也是由Na⁺电导增加介导的。我们得出结论，汇合的原代培养大鼠肝细胞能够进行RVI以及RVD后RVI。在这个系统中，高渗应激导致细胞膜Na⁺电导显著增加。与传导性Na⁺内流一致，细胞K⁺随后通过Na⁺/K⁺-ATP酶的激活而增加。Na⁺/H⁺交换在大鼠肝细胞容积调节中的额外作用仍有待确定。
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