K+ currents activated by depolarization in cardiac fibroblasts

被引:73
作者
Shibukawa, Y
Chilton, EL
MacCannell, KA
Clark, RB
Giles, WR [1 ]
机构
[1] Univ Calif San Diego, Whitaker Inst Biomed Engn, Dept Bioengn, La Jolla, CA 92093 USA
[2] Univ Calgary, Fac Med, Dept Physiol & Biophys, Calgary, AB, Canada
基金
加拿大健康研究院;
关键词
D O I
10.1529/biophysj.104.054429
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
K+ currents expressed in freshly dispersed rat ventricular fibroblasts have been studied using whole-cell patch-clamp recordings. Depolarizing voltage steps from a holding potential of -90 mV activated time- and voltage-dependent outward currents at membrane potentials positive to similar to-30 mV. The relatively slow activation kinetics exhibited strong dependence on the membrane potential. Selected changes in extracellular K+ concentration ([K+](o)) revealed that the reversal potentials of the tail currents changed as expected for a K+ equilibrium potential. The activation and inactivation kinetics of this K+ current, as well as its recovery from inactivation, were well-fitted by single exponential functions. The steady-state inactivation was well described by a Boltzmann function with a half-maximal inactivation potential (V-0.5) of -24 mV. Increasing [K+](o) (from 5 to 100 mM) shifted this V-0.5 in the hyperpolarizing direction by -11 mV. Inactivation was slowed by increasing [K+](o) to 100 mM, and the rate of recovery from inactivation was decreased after increasing [K+](o). Block of this K+ current by extracellular tetraethylammonium also slowed inactivation. These [K+](o)-induced changes and tetraethylammonium effects suggest an important role for a C-type inactivation mechanism. This K+ current was sensitive to dendrotoxin-I (100 nM) and rTityustoxin K alpha (50 nM).
引用
收藏
页码:3924 / 3935
页数:12
相关论文
共 55 条
[1]   VOLTAGE CLAMP AND TRACER FLUX DATA - EFFECTS OF A RESTRICTED EXTRA-CELLULAR SPACE [J].
ATTWELL, D ;
EISNER, D ;
COHEN, I .
QUARTERLY REVIEWS OF BIOPHYSICS, 1979, 12 (03) :213-261
[3]   MODULATION OF K+ CURRENT BY FREQUENCY AND EXTERNAL [K+] - A TALE OF 2 INACTIVATION MECHANISMS [J].
BAUKROWITZ, T ;
YELLEN, G .
NEURON, 1995, 15 (04) :951-960
[4]   EFFECTS OF ACTION-POTENTIAL DURATION ON EXCITATION-CONTRACTION COUPLING IN RAT VENTRICULAR MYOCYTES - ACTION-POTENTIAL VOLTAGE-CLAMP MEASUREMENTS [J].
BOUCHARD, RA ;
CLARK, RB ;
GILES, WR .
CIRCULATION RESEARCH, 1995, 76 (05) :790-801
[5]  
Brew HM, 1995, J NEUROSCI, V15, P8011
[6]   Fibroblast network in rabbit sinoatrial node - Structural and functional identification of homogeneous and heterogeneous cell coupling [J].
Camelliti, P ;
Green, CR ;
LeGrice, I ;
Kohl, P .
CIRCULATION RESEARCH, 2004, 94 (06) :828-835
[7]   K+ currents regulate the resting membrane potential, proliferation, and contractile responses in ventricular fibroblasts and myofibroblasts [J].
Chilton, L ;
Ohya, S ;
Freed, D ;
George, E ;
Drobic, V ;
Shibukawa, Y ;
MacCannell, KA ;
Imaizumi, Y ;
Clark, RB ;
Dixon, IMC ;
Giles, WR .
AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY, 2005, 288 (06) :H2931-H2939
[8]  
Chilton L, 2003, BIOPHYS J, V84, p225A
[9]  
CHILTON L, 2003, J PHYSIOL-LONDON, V551, pA35
[10]   TETRAETHYLAMMONIUM BLOCKADE DISTINGUISHES 2 INACTIVATION MECHANISMS IN VOLTAGE-ACTIVATED K+ CHANNELS [J].
CHOI, KL ;
ALDRICH, RW ;
YELLEN, G .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1991, 88 (12) :5092-5095