LARGE-CONDUCTANCE ION CHANNEL MEASURED BY WHOLE-CELL VOLTAGE CLAMP IN SINGLE CARDIAC-CELLS - MODULATION BY BETA-ADRENERGIC STIMULATION AND INHIBITION BY OCTANOL

被引:19
作者
POTT, L
MECHMANN, S
机构
[1] Institut für Zellphysiologie, Ruhr-Universität Bochum, Bochum
关键词
β-adrenoceptor; Ca-activated ion channel; cardiac myocytes; gap junction; ion channel; maxichannel;
D O I
10.1007/BF01868685
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Membrane currents in single cardiac myocytes from adult guinea pigs were studied by means of the patch-clamp technique (whole-cell mode). During spontaneous or caffeine-induced Ca2+ release from the sarcoplasmic reticulum openings of a novel ion channel with large unitary conductance (280 pS) can be recorded. The density of these channels and/or its open-state probability are unusually low. On average in the whole-cell mode simultaneous maximum superposition of only four channels is observed. Opening events of this channel require an intracellular Ca2+ transient. Activation by [Ca2+]i, however, seems to be indirect; maximum opening activity occurs with a delay of several hundred milliseconds after peak [Ca2+]i. Single-channel activity can be enhanced by a cyclic AMP dependent process via β-adrenergic stimulation of a cell. This can also be mimicked by caffeine, most likely via inhibition of phosphodiesterase. Octanol, an inhibitor of gap-junctional coupling in a variety of tissues. causes a concentration-dependent and reversible decrease in single-channel activity. Unitary conductance is not affected by octanol. The low density of these channels in cardiac membranes and their poor selectivity render and role in normal cardiac electrical activity unlikely. A possible relation of the channel to cardiac gap junctions is discussed. © 1990 Springer-Verlag New York Inc.
引用
收藏
页码:189 / 199
页数:11
相关论文
共 40 条
[1]  
BECHEM M, 1983, EUR J CELL BIOL, V31, P366
[2]   REMOVAL OF CA CURRENT INACTIVATION IN DIALYZED GUINEA-PIG ATRIAL CARDIOBALLS BY CA CHELATORS [J].
BECHEM, M ;
POTT, L .
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1985, 404 (01) :10-20
[3]  
BEUCKELMANN DJ, 1989, J PHYSL, V314, pP110
[4]   BETA-ADRENERGIC MODULATION OF TRANSIENT INWARD CURRENT IN GUINEA-PIG CARDIAC MYOCYTES - EVIDENCE FOR REGULATION OF CA-2+-RELEASE FROM SARCOPLASMIC-RETICULUM BY A CYCLIC-AMP DEPENDENT MECHANISM [J].
BOLLER, M ;
POTT, L .
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY, 1989, 415 (03) :276-288
[5]   CAFFEINE-INDUCED CA-2+ RELEASE ACTIVATES CA-2+ EXTRUSION VIA NA+-CA-2+ EXCHANGER IN CARDIAC MYOCYTES [J].
CALLEWAERT, G ;
CLEEMANN, L ;
MORAD, M .
AMERICAN JOURNAL OF PHYSIOLOGY, 1989, 257 (01) :C147-C152
[6]   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
[7]   DECOUPLING OF HEART-MUSCLE CELLS - CORRELATION WITH INCREASED CYTOPLASMIC CALCIUM ACTIVITY AND WITH CHANGES OF NEXUS ULTRASTRUCTURE [J].
DAHL, G ;
ISENBERG, G .
JOURNAL OF MEMBRANE BIOLOGY, 1980, 53 (01) :63-75
[8]   EFFECT OF SEVERAL UNCOUPLERS OF CELL-TO-CELL COMMUNICATION ON GAP JUNCTION MORPHOLOGY IN MAMMALIAN HEART [J].
DELEZE, J ;
HERVE, JC .
JOURNAL OF MEMBRANE BIOLOGY, 1983, 74 (03) :203-215
[10]   A MODEL OF CARDIAC ELECTRICAL-ACTIVITY INCORPORATING IONIC PUMPS AND CONCENTRATION CHANGES [J].
DIFRANCESCO, D ;
NOBLE, D .
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES, 1985, 307 (1133) :353-398