Pedersen K A, Jørgensen N K, Jensen B S, Olesen S P
Department of Medical Physiology, The Panum Institute, University of Copenhagen, Denmark.
Pflugers Arch. 2000 May;440(1):153-6. doi: 10.1007/s004240000269.
The effect of changes in pH on the gating properties of the cloned human intermediate-conductance, Ca2+-activated K+ channel (hIK) was studied using the patch-clamp technique. Multi-channel inside-out recordings of patches from HEK-293 cells stably expressing hIK channels revealed that the channel activity is modulated by changes in intracellular pH (pHi). Changes in extracellular pH (pHo) in the range from pH 6.0 to 8.2 did not affect the hIK whole-cell current. Intracellular acidification gradually decreased the activity of the hIK channel, approaching zero activity at pHi 6.0. Decreasing pHi altered neither the conductance nor the inward rectification of hIK channels. The proton-induced inhibition of the multi-channel hIK patch current could not be counteracted by increasing the cytosolic Ca2+ concentration to 30 microM. The molecular sensory mechanism underlying the proton-induced modulation of hIK gating is at present unknown.
采用膜片钳技术研究了pH值变化对克隆的人中间电导钙激活钾通道（hIK）门控特性的影响。对稳定表达hIK通道的HEK-293细胞进行多通道内面向外膜片记录，结果表明通道活性受细胞内pH值（pHi）变化的调节。细胞外pH值（pHo）在6.0至8.2范围内的变化不影响hIK全细胞电流。细胞内酸化逐渐降低hIK通道的活性，在pHi为6.0时接近零活性。降低pHi既不改变hIK通道的电导，也不改变其内向整流特性。将胞质Ca2+浓度提高到30μM并不能抵消质子诱导的多通道hIK膜片电流抑制作用。目前尚不清楚质子诱导的hIK门控调节的分子传感机制。
