对照大鼠和患有视网膜营养不良大鼠的培养周细胞中的膜电压和全细胞电流。
Membrane voltage and whole-cell currents in cultured pericytes of control rats and rats with retinal dystrophy.
作者信息
Wagner U, Wiederholt M
机构信息
Institut für Klinische Physiologie, Universitätsklinikum Benjamin Franklin, Freie Universität Berlin, Germany.
出版信息
Curr Eye Res. 1996 Oct;15(10):1045-53. doi: 10.3109/02713689609017654.
PURPOSE
Retinal vascular changes are associated with retinitis pigmentosa in man and the retinal dystrophy of the Royal College of Surgeons (RCS) rat. Recently we demonstrated that retinal capillary pericytes possess electrical membrane characteristics typical for smooth muscle cells and may thus regulate retinal blood flow in vivo.
METHODS
In the present study we compared cultured pericytes of 5-7 day old RCS and control rats by measurement of membrane voltage (Vmem) with microelectrodes and currents with the whole-cell configuration of the patch-clamp technique.
RESULTS
Resting membrane voltage (-37.6 mV +/- 1.0 mV, n = 106 and -36.6 mV +/- 0.7 mV, n = 102, respectively) and whole-cell currents, which are mainly determined by a potassium conductance, were comparable in pericytes of control and RCS rats. The electrogenic component of the Na(+)-K(+)-ATPase in RCS rat pericytes was reduced, because depolarization of their membrane voltage by Na(+)-K(+)-ATPase inhibitor ouabain (10(-4) mol.1-1 or K+ free solution was significantly decreased compared to control pericytes. Norepinephrine (10(-5) mol.1-1) depolarized Vmem of control rat pericytes by delta 7.0 mV +/- 1.3 mV (n = 7), whereas it hyperpolarized Vmem of RCS rat pericytes by delta 2.0 mV +/- 0.8 mV (n = 11). The depolarization of Vmem by histamine (10(-5) mol.1-1) was significantly reduced in pericytes of RCS rats (delta 2.6 mV +/- 0.4 mV, n = 7) compared to control pericytes (delta 4.3 mV +/- 0.5 mV, n = 6). In pericytes of RCS rats ATP-induced activation of inward and outward currents and depolarization of membrane voltage were also significantly reduced.
CONCLUSIONS
The data indicate that there are differences in the electrophysiological properties of retinal capillary pericytes of 5-7 days old RCS and control rats. Whereas resting membrane voltage and K+ conductance are comparable in both groups, there are significant differences in the electrical activity of Na(+)-K(+)-ATPase and in the effects of vasoactive substances on the membrane voltage and currents. These differences might contribute to the vascular changes observed in RP, and possibly accelerate the progress of retinal dystrophy.
目的
视网膜血管变化与人的色素性视网膜炎及皇家外科学院（RCS）大鼠的视网膜营养不良有关。最近我们证明视网膜毛细血管周细胞具有平滑肌细胞典型的电膜特性，因此可能在体内调节视网膜血流。
方法
在本研究中，我们通过用微电极测量膜电压（Vmem）以及用膜片钳技术的全细胞配置测量电流，比较了5 - 7日龄RCS大鼠和对照大鼠的培养周细胞。
结果
对照大鼠和RCS大鼠周细胞的静息膜电压（分别为-37.6 mV±1.0 mV，n = 106和-36.6 mV±0.7 mV，n = 102）以及主要由钾电导决定的全细胞电流相当。RCS大鼠周细胞中Na(+)-K(+)-ATP酶的生电成分减少，因为与对照周细胞相比，Na(+)-K(+)-ATP酶抑制剂哇巴因（10(-4) mol·L-1）或无钾溶液使它们的膜电压去极化明显降低。去甲肾上腺素（10(-5) mol·L-1）使对照大鼠周细胞的Vmem去极化7.0 mV±1.3 mV（n = 7），而使RCS大鼠周细胞的Vmem超极化2.0 mV±0.8 mV（n = 11）。与对照周细胞（4.3 mV±0.5 mV，n = 6）相比，组胺（10(-5) mol·L-1）使RCS大鼠周细胞的Vmem去极化明显降低（2.6 mV±0.4 mV，n = 7）。在RCS大鼠周细胞中，ATP诱导的内向和外向电流激活以及膜电压去极化也明显降低。
结论
数据表明5 - 7日龄RCS大鼠和对照大鼠的视网膜毛细血管周细胞电生理特性存在差异。虽然两组的静息膜电压和K+电导相当，但Na(+)-K(+)-ATP酶的电活动以及血管活性物质对膜电压和电流的影响存在显著差异。这些差异可能导致色素性视网膜炎中观察到的血管变化，并可能加速视网膜营养不良的进展。
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