Transient outward K+ channels in vesicles derived from frog skeletal muscle plasma membranes

被引:8
作者
Camacho, J
Delay, MJ
Vazquez, M
Arguello, C
Sanchez, JA
机构
[1] IPN, CINVESTAV, DEPT PHARMACOL & TOXICOL, MEXICO CITY 07000, DF, MEXICO
[2] IPN, CINVESTAV, DEPT PATHOL, MEXICO CITY 07000, DF, MEXICO
[3] Univ Nacl Autonoma Mexico, DEPT PHYSIOL, SCH MED, MEXICO CITY, DF, MEXICO
[4] AXON INSTRUMENTS, FOSTER CITY, CA 94404 USA
关键词
D O I
10.1016/S0006-3495(96)79214-7
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
Whole-cell voltage-clamp experiments were performed in vesicles derived from frog skeletal muscle plasma membranes. Capacitance measurements showed that these vesicles lack invaginations. In solutions containing K+, transient outward currents with reversal potentials close to E(K) were recorded with a maximum potassium conductance of 0.3 mS/cm(2). These currents inactivated in a voltage-dependent manner with a time constant of decay that reached a limiting value of 26 ms at large depolarizations. The steady-state inactivation reached half-maximum values at -66 mV. Transient currents were completely blocked with 5 mM 4-aminopyridine. Single-channel recordings made in inside-out excised patches from the vesicles had ensemble averages with characteristics similar to those of the macroscopic currents, although with significantly faster inactivation time constants. The single-channel chord conductance was 21 pS when the pipette and bath solutions contained 2.5 mM and 120 mM KCl, respectively. It is concluded that these vesicles contain potassium channels that are very similar to A channels found in neurons and other cells.
引用
收藏
页码:171 / 181
页数:11
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