Kominkova Viera, Malekova Lubica, Tomaskova Zuzana, Slezak Peter, Szewczyk Adam, Ondrias Karol
Institute of Molecular Physiology and Genetics, Centre of Excellence for Cardiovascular Research, Slovak Academy of Sciences, 83334 Bratislava, Slovakia.
Biochim Biophys Acta. 2010 Jun-Jul;1797(6-7):1300-12. doi: 10.1016/j.bbabio.2010.02.031. Epub 2010 Mar 4.
We report the effects of ATP and Mg2+ on the activity of intracellular chloride channels. Mitochondrial and lysosomal membrane vesicles isolated from rat hearts were incorporated into bilayer lipid membranes, and single chloride channel currents were measured. The observed chloride channels (n=112) possessed a wide variation in single channel parameters and sensitivities to ATP. ATP (0.5-2 mmol/l) modulated and/or inhibited the chloride channel activities (n=38/112) in a concentration-dependent manner. The inhibition effect was irreversible (n=5/93) or reversible (n=15/93). The non-hydrolysable ATP analogue AMP-PNP had a similar inhibition effect as ATP, indicating that phosphorylation did not play a role in the ATP inhibition effect. ATP modulated the gating properties of the channels (n=6/93), decreased the channels' open dwell times and increased the gating transition rates. ATP (0.5-2 mmol/l) without the presence of Mg2+ decreased the chloride channel current (n=12/14), whereas Mg2+ significantly reversed the effect (n=4/4). We suggest that ATP-intracellular chloride channel interactions and Mg2+ modulation of these interactions may regulate different physiological and pathological processes.
我们报告了ATP和Mg2+对细胞内氯离子通道活性的影响。从大鼠心脏分离出的线粒体和溶酶体膜囊泡被整合到双层脂质膜中，并测量了单个氯离子通道电流。观察到的氯离子通道（n = 112）在单通道参数和对ATP的敏感性方面存在很大差异。ATP（0.5 - 2 mmol/L）以浓度依赖的方式调节和/或抑制氯离子通道活性（n = 38/112）。抑制作用是不可逆的（n = 5/93）或可逆的（n = 15/93）。不可水解的ATP类似物AMP - PNP具有与ATP相似的抑制作用，表明磷酸化在ATP抑制作用中不起作用。ATP调节通道的门控特性（n = 6/93），减少通道的开放驻留时间并增加门控转换速率。不存在Mg2+时，ATP（0.5 - 2 mmol/L）降低氯离子通道电流（n = 12/14），而Mg2+显著逆转该效应（n = 4/4）。我们认为ATP与细胞内氯离子通道的相互作用以及Mg2+对这些相互作用的调节可能参与调控不同的生理和病理过程。
