HIGH SELECTIVITY OF THE I(F) CHANNEL TO NA+ AND K+ IN RABBIT ISOLATED SINOATRIAL NODE CELLS

被引:33
作者
HO, WK [1 ]
BROWN, HF [1 ]
NOBLE, D [1 ]
机构
[1] UNIV OXFORD,PHYSIOL LAB,OXFORD OX1 3PT,ENGLAND
来源
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY | 1994年 / 426卷 / 1-2期
关键词
HYPERPOLARIZATION-ACTIVATED INWARD CURRENT; SINOATRIAL NODE CELLS; SELECTIVE PERMEABILITY; LI+; RB+; CS+;
D O I
10.1007/BF00374672
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
The ionic selectivity of the hyperpolarization-activated inward current (i(f)) channel to monovalent cations was investigated in single isolated sinoatrial node cells of the rabbit using the whole-cell patch-clamp technique. With a 140 mM K+ pipette, replacement of 90% external Na+ by Li+ caused a -24.5 mV shift of the fully activated current/voltage I/V curve without a significant decrease of the slope conductance. With a 140 mM Cs+ pipette, the i(f) current decreased almost proportionally to the decrease in external [Na+](o) as Li+ was substituted. These responses are practically the same as those observed with N-methyl glucamine (NMG(+)) substitution, suggesting that the relative permeability of Li+ compared with Na+ for the i(f) channel is as low as that of NMG(+). When Cs+ or Rb+ was substituted for internal K+, the fully activated I/V relationship for i(f) showed strong inward rectification with a positive reversal potential, indicating low permeability of the i(f) channel for Cs+ and Rb+. These results show that the i(f) channel is highly selective for Na+ and K+ and will not pass the similar ions Li+ and Rb+. Such a high degree of selectivity is unique and may imply that the structure of the i(f) channel differs greatly from that of other Na+ and K+ conducting channels.
引用
收藏
页码:68 / 74
页数:7
相关论文
共 27 条
[1]   THE PERMEABILITY OF ENDPLATE CHANNELS TO MONO-VALENT AND DIVALENT METAL-CATIONS [J].
ADAMS, DJ ;
DWYER, TM ;
HILLE, B .
JOURNAL OF GENERAL PHYSIOLOGY, 1980, 75 (05) :493-510
[3]   INWARD CURRENT CHANNELS ACTIVATED BY INTRACELLULAR CA IN CULTURED CARDIAC-CELLS [J].
COLQUHOUN, D ;
NEHER, E ;
REUTER, H ;
STEVENS, CF .
NATURE, 1981, 294 (5843) :752-754
[4]   PACEMAKING IN RABBIT ISOLATED SINOATRIAL NODE CELLS DURING CS+ BLOCK OF THE HYPERPOLARIZATION-ACTIVATED CURRENT IF [J].
DENYER, JC ;
BROWN, HF .
JOURNAL OF PHYSIOLOGY-LONDON, 1990, 429 :401-409
[5]   PROPERTIES OF THE HYPERPOLARIZING-ACTIVATED CURRENT (IF) IN CELLS ISOLATED FROM THE RABBIT SINOATRIAL NODE [J].
DIFRANCESCO, D ;
FERRONI, A ;
MAZZANTI, M ;
TROMBA, C .
JOURNAL OF PHYSIOLOGY-LONDON, 1986, 377 :61-88
[6]   CHARACTERIZATION OF SINGLE PACEMAKER CHANNELS IN CARDIAC SINOATRIAL NODE CELLS [J].
DIFRANCESCO, D .
NATURE, 1986, 324 (6096) :470-473
[7]   A STUDY OF THE IONIC NATURE OF THE PACE-MAKER CURRENT IN CALF PURKINJE-FIBERS [J].
DIFRANCESCO, D .
JOURNAL OF PHYSIOLOGY-LONDON, 1981, 314 (MAY) :377-393
[8]   BLOCK AND ACTIVATION OF THE PACE-MAKER CHANNEL IN CALF PURKINJE-FIBERS - EFFECTS OF POTASSIUM, CESIUM AND RUBIDIUM [J].
DIFRANCESCO, D .
JOURNAL OF PHYSIOLOGY-LONDON, 1982, 329 (AUG) :485-507
[9]   THE PERMEABILITY OF THE ENDPLATE CHANNEL TO ORGANIC CATIONS IN FROG-MUSCLE [J].
DWYER, TM ;
ADAMS, DJ ;
HILLE, B .
JOURNAL OF GENERAL PHYSIOLOGY, 1980, 75 (05) :469-492
[10]   ION PERMEATION THROUGH HYPERPOLARIZATION-ACTIVATED MEMBRANE CHANNELS (Q-CHANNELS) IN THE LOBSTER STRETCH-RECEPTOR NEURON [J].
EDMAN, A ;
GRAMPP, W .
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1989, 413 (03) :249-255