Hordejuk Renata, Lobanov Nikolai A, Kicinska Anna, Szewczyk Adam, Dolowy Krzysztof
Department of Biophysics, Agriculture University, Warsaw, Poland.
Mol Membr Biol. 2004 Sep-Oct;21(5):307-13. doi: 10.1080/10647440400003899.
We report here that large conductance K(+) selective channel in adrenal chromaffin granules is controlled by pH. We measured electrogenic influx of (86)Rb(+) into chromaffin granules prepared from bovine adrenal gland medulla. The (86)Rb(+) influx was inhibited by acidic pH. Purified chromaffin granule membranes were also fused with planar lipid bilayer. A potassium channel with conductance of 432+/-9 pS in symmetric 450 mM KCl was observed after reconstitution into lipid bilayer. The channel activity was unaffected by charybdotoxin, a blocker of the Ca(2+)-activated K(+) channel of large conductance. It was observed that acidification to pH 6.4 cis side of the membrane lowered the channel open probability and single channel conductance. Whereas only weak influence on the single channel current amplitude and open probability were observed upon lowering of the pH at the trans side. We conclude that a pH-sensitive large conductance potassium channel operates in the chromaffin granule membrane.
我们在此报告，肾上腺嗜铬颗粒中的大电导钾离子选择性通道受pH值调控。我们测量了86Rb+向从牛肾上腺髓质制备的嗜铬颗粒中的电源性内流。酸性pH值抑制了86Rb+的内流。纯化的嗜铬颗粒膜也与平面脂质双层融合。在重构成脂质双层后，观察到在对称的450 mM KCl中电导为432±9 pS的钾通道。该通道活性不受大电导钙激活钾通道阻滞剂蝎毒素的影响。观察到将膜的顺式侧酸化至pH 6.4会降低通道开放概率和单通道电导。而在反式侧降低pH值时，仅观察到对单通道电流幅度和开放概率的微弱影响。我们得出结论，一种pH敏感的大电导钾通道在嗜铬颗粒膜中起作用。
