von Beckerath N, Nees S, Neumann F J, Krebs B, Juchem G, Schömig A
Deutsches Herzzentrum and 1.Medizinische Klinik, Technische Universität München, Munich, Germany.
Cardiovasc Res. 2000 Jun;46(3):569-78. doi: 10.1016/s0008-6363(00)00055-9.
The purpose of this study was to describe passive electrical properties and major membrane currents in coronary pericytes.
78 single, cultured bovine pericytes were studied with the patch-clamp technique in the whole-cell mode.
The membrane potential of the cells was -48.9+/-9.6 mV (mean+/-S.D.) with 5 mM and -23.2+/-2.2 mV with 60 mM extracellular K+. The membrane capacitance was 150.2+/-123.2 pF. The current-voltage relation of the pericytes was dominated by an inward current at hyperpolarized potentials and an outward current at depolarized potentials. Increasing extracellular K+ from 5 to 60 mM led to an increase of the inward current and to a shift of this current to more depolarized potentials. The inward current was very sensitive to extracellular barium (50 microM). The maximum slope conductance of the cells at hyperpolarized potentials was 2.9+/-2.8 nS. Inward rectification of whole-cell currents was steep (slope factor = 6.8 mV). With elevated external K+ the outward current reversed near the potassium equilibrium potential. Onset of the outward current was sigmoid and inactivation of this current was monoexponential, slow (time constant = 12.8 s) and incomplete. Voltage-dependence of outward current steady-state activation was steep (slope factor = 4.6 mV). The outward current was very sensitive to 4-aminopyridine (dissociation constant = 0.1 mM). The maximum slope conductance at depolarized potentials was 16.6+/-15.6 nS.
We report for the first time, patch-clamp recordings from coronary pericytes. An inward rectifier and a voltage-dependent K+ current were identified and characterized. Regulation of these currents may influence coronary blood flow.
本研究旨在描述冠状动脉周细胞的被动电特性和主要膜电流。
采用膜片钳技术的全细胞模式对78个单独培养的牛周细胞进行研究。
细胞在细胞外钾浓度为5 mM时的膜电位为-48.9±9.6 mV（平均值±标准差），在细胞外钾浓度为60 mM时为-23.2±2.2 mV。膜电容为150.2±123.2 pF。周细胞的电流-电压关系在超极化电位时以内向电流为主，在去极化电位时以外向电流为主。将细胞外钾浓度从5 mM增加到60 mM导致内向电流增加，并使该电流向更正的去极化电位偏移。内向电流对细胞外钡（50 μM）非常敏感。细胞在超极化电位时的最大斜率电导为2.9±2.8 nS。全细胞电流的内向整流很陡（斜率因子=6.8 mV）。随着细胞外钾浓度升高，外向电流在钾平衡电位附近反转。外向电流的起始呈S形，该电流的失活为单指数、缓慢（时间常数=12.8 s）且不完全。外向电流稳态激活的电压依赖性很陡（斜率因子=4.6 mV）。外向电流对4-氨基吡啶非常敏感（解离常数=0.1 mM）。细胞在去极化电位时的最大斜率电导为16.6±15.6 nS。
我们首次报道了冠状动脉周细胞的膜片钳记录。鉴定并表征了一种内向整流器和一种电压依赖性钾电流。这些电流的调节可能会影响冠状动脉血流。
