Caffeine-evoked, calcium-sensitive membrane currents in rabbit aortic endothelial cells.
Caffeine-evoked, calcium-sensitive membrane currents in rabbit aortic endothelial cells.
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兔主动脉内皮细胞中咖啡因诱发的钙敏感膜电流。
DOI：
10.1111/j.1476-5381.1995.tb16330.x
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发表时间：
1995
影响因子：
7.3
通讯作者：
Adams,DJ
中科院分区：
文献类型：
--
作者：
Rusko,J;VanSlooten,G;Adams,DJ
1Single cell photometry and whole‐cell patch clamp recording were used to study caffeine‐induced intracellular Ca2+signals and membrane currents, respectively, in endothelial cells freshly dissociated from rabbit aorta.2Caffeine (5 mM) evoked a transient increase in [Ca2+]iin fura‐2‐loaded endothelial cells. Pretreatment of cells with lO μMryanodine did not alter resting [Ca2+]ibut irreversibly inhibited the caffeine‐induced rise in [Ca2+]i. The caffeine‐induced increase in [Ca2+]iwas not attenuated by the removal of extracellular Ca2+and did not stimulate the rate of Mn2+quench of fura‐2 fluorescence.3Bath application of caffeine evoked a dose‐ and voltage‐dependent outward current. The rate of onset and amplitude of the caffeine‐evoked outward current increased with higher caffeine concentrations and membrane depolarization. The relationship between caffeine‐evoked current amplitude and membrane potential was non linear, suggesting that the channels underlying the current are voltage‐sensitive.4In the absence of extracellular Ca2+, the amplitude of the caffeine‐evoked outward current was reduced by approximately 50% but the duration of the current was prolonged compared to that observed in the presence of external Ca2+. Ca2+‐free external solutions produced an unexpected increase in both the frequency and amplitude of spontaneous transient outward currents (STOCs).5Inclusion of heparin (10 μg ml−1) in the patch pipette abolished the acetylcholine (ACh)‐induced outward current but failed to inhibit either STOCs or the caffeine‐evoked outward current in native endothelial cells. In the absence of extracellular Ca2+, heparin did not affect either STOCs or the caffeine‐induced outward current.6Externally applied tetraethylammonium ions (TEA, 3–10 mM) reversibly inhibited unitary Ca2+‐activated K+currents and STOCs in endothelial cells but failed to inhibit completely the outward current evoked by 20 mM caffeine.7Bath application of 0.1 mM zinc ion (Zn2+), a chloride channel blocker, did not affect unitary currents or STOCs but reduced the amplitude of the caffeine‐evoked current by >75% compared to control. Replacement of extracellular NaCl with Na gluconate also reduced the amplitude of the caffeine‐induced outward current. Bath application of 0.1 mM Zn2+and 10 mM TEA completely blocked the caffeine‐evoked outward current in endothelial cells.8Caffeine‐induced Ca2+release from intracellular stores evokes a transient rise in [Ca2+]iwhich is correlated with a large, transient outward current. The ionic dependence and inhibition of the caffeine‐sensitive current by TEA and Zn2+suggests that Ca2+‐activated K+and Cl−conductances contribute to the caffeine response in rabbit aortic endothelial cells.
