Miao K, Wondergem R, Hossler F E, Joyner W L
Department of Physiology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614-0002.
J Cell Physiol. 1993 Sep;156(3):550-9. doi: 10.1002/jcp.1041560314.
The transmembrane potential (Vm) of vascular endothelial cells (EC) is an important property that may be involved in intra- and intercellular signal transduction for various vascular functions. In this study, Vm of intact aortic and vena caval EC from hamsters were measured using conventional microelectrodes. Vascular strips with the luminal surface upwards were suffused in a tissue chamber with Krebs solution in physiological conditions. The resting Vm of aortic and vena caval EC was found to be -40 +/- 1 mV (n = 55) and -43 +/- 1 mV (n = 15), respectively. The Vm recordings were confirmed to have originated from EC by scanning and transmission electron microscopy combined with the comparison of electrical recordings between normal and endothelium-denuded aortic strips. The input resistance varied from 10-240 M omega, which implied the presence of electrical coupling between vascular EC. Elevating the K+ level in the suffusate from 4.7 mM to 50 and 100 mM depolarized aortic EC by 19% and 29% and vena caval EC by 18% and 29%, respectively. These low percentages indicated a relatively small contribution of [K+] to the resting Vm of vascular EC. A positive correlation (r > 0.69) between the resting Vm and the magnitude of depolarization by the high [K+]o may be related to the involvement of voltage-dependent K+ channels. The hyperpolarization caused by lowering both [Na+]o and [Cl-]o suggested the disengagement of some electrogenic transport systems in the membrane, such as a Na(+)-K(+)-Cl- cotransporter. The transference number (t(ion)), as an index of membrane conductance for specific ions, was calculated for K+ (15-20%), Na+ (16%), and Cl- (9-15%), demonstrating that both Na+ and Cl- as well as K+ contribute to the overall resting Vm. Our study documented some basic electrophysiology of the vascular EC when both structural and functional properties of the cell were maintained, thus furthering the understanding of the essential role of endothelial cells in mediating vascular functions.
血管内皮细胞（EC）的跨膜电位（Vm）是一项重要特性，可能参与多种血管功能的细胞内和细胞间信号转导。在本研究中，使用传统微电极测量了仓鼠完整主动脉和腔静脉内皮细胞的Vm。将管腔表面向上的血管条置于生理条件下装有 Krebs 溶液的组织槽中。发现主动脉和腔静脉内皮细胞的静息Vm分别为-40±1 mV（n = 55）和-43±1 mV（n = 15）。通过扫描和透射电子显微镜，结合正常和去内皮主动脉条之间电记录的比较，证实Vm记录源自内皮细胞。输入电阻在10 - 240 MΩ之间变化，这意味着血管内皮细胞之间存在电耦合。将灌注液中的K⁺水平从4.7 mM提高到50 mM和100 mM时，主动脉内皮细胞分别去极化19%和29%，腔静脉内皮细胞分别去极化18%和29%。这些低百分比表明[K⁺]对血管内皮细胞静息Vm的贡献相对较小。静息Vm与高[K⁺]o引起的去极化幅度之间的正相关（r > 0.69）可能与电压依赖性K⁺通道的参与有关。降低[Na⁺]o和[Cl⁻]o引起的超极化表明膜中一些电生转运系统（如Na⁺-K⁺-Cl⁻共转运体）的脱离。作为特定离子膜电导指标的迁移数（t(ion)），计算得出K⁺为15 - 20%，Na⁺为16%，Cl⁻为9 - 15%，表明Na⁺、Cl⁻以及K⁺都对整体静息Vm有贡献。我们的研究记录了细胞结构和功能特性均得以维持时血管内皮细胞的一些基本电生理情况，从而进一步加深了对内皮细胞在介导血管功能中重要作用的理解。
