PROPERTIES OF SPONTANEOUS INWARD CURRENTS IN RABBIT PULMONARY-ARTERY SMOOTH-MUSCLE CELLS

被引:40
作者
HOGG, RC [1 ]
WANG, Q [1 ]
HELLIWELL, RM [1 ]
LARGE, WA [1 ]
机构
[1] ST GEORGE HOSP,SCH MED,DEPT PHARMACOL & CLIN PHARMACOL,LONDON SW17 0RE,ENGLAND
来源
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY | 1993年 / 425卷 / 3-4期
基金
英国惠康基金;
关键词
ARTERIAL SMOOTH MUSCLE; CALCIUM-ACTIVATED CHLORIDE CURRENTS;
D O I
10.1007/BF00374172
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
Spontaneous inward and outward currents were studied with perforated patch recording in freshly dispersed rabbit pulmonary artery smooth muscle cells. With physiological potassium concentrations, spontaneous outward and inward currents were recorded at negative membrane potentials. Ion substitution experiments revealed that the outward and inward currents were respectively potassium and chloride conductance increases. Both conductances were abolished by bath application of caffeine (2-10 mM), which releases calcium from internal stores. The rise time and half-decay time of spontaneous potassium currents were both about 25 ms. The spontaneous chloride current has a rise time of 30 ms and decayed exponentially with a time constant (tau) of 70 ms at -50 mV. The tau value was increased by depolarization and increased e-fold for a change of 99 mV in membrane potential. In every cell examined when the spontaneous currents occurred as biphasic events, typically between -20 mV and -40 mV, outward currents preceded inward currents in over 90% of these events whereas the inward current always preceded the outward current in caffeine- and noradrenaline-evoked responses. An explanation for these data is that there may be localization of some chloride channels with respect to the caffeine-sensitive calcium store.
引用
收藏
页码:233 / 240
页数:8
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