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首页> 美国卫生研究院文献>The Journal of Physiology >Proton modulation of ion channels in isolated horizontal cells of the goldfish retina
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Proton modulation of ion channels in isolated horizontal cells of the goldfish retina

机译：分离的金鱼视网膜水平细胞中离子通道的质子调节

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Transient changes in extracellular pH (pHo) occur in the retina and may have profound effects on neurotransmission and visual processing due to the pH sensitivity of ion channels. The present study characterized the effects of acidification on the activity of membrane ion channels in isolated horizontal cells (HCs) of the goldfish retina using whole-cell patch-clamp recording. Currents recorded from HCs were characterized by prominent inward rectification at potentials negative to −80 mV, a negative slope conductance between −70 and −40 mV, a sustained inward current, and outward rectification positive to 40 mV. Inward currents were identified as those of inward rectifier K+ (Kir) channels and Ca2+ channels by their sensitivity to 10 mm Cs+ or 20 μm Cd2+, respectively. Both of these currents were reduced when pHo decreased from 7.8 to 6.8. Glutamate (1 mm)-activated currents were also identified, as were hemichannel currents that were enhanced by removal of extracellular Ca2+ and application of 1 mm quinidine. Both glutamate-activated and hemichannel currents were suppressed by a similar reduction of pHo. When all of these H+-inhibited currents were blocked, a small, sustained inward current at −60 mV increased following a decrease in pHo from 7.8 to 6.8. In addition, slope conductance between −70 and −20 mV increased during this acidification. Suppression of this H+-activated current by removal of extracellular Na+, and an extrapolated Erev near ENa, indicated that this current was carried predominantly by Na+ ions.
机译：细胞外pH（pHo）的瞬时变化发生在视网膜中，由于离子通道对pH的敏感性，可能会对神经传递和视觉加工产生深远影响。本研究利用全细胞膜片钳记录来表征酸化对金鱼视网膜分离水平细胞（HCs）中膜离子通道活性的影响。从HC记录的电流的特征在于，在-80 mV的负电势下具有显着的向内整流，在-70和-40 mV之间的负斜率电导，持续的向内电流以及对40 mV呈正向的向外整流。通过对10 mm Cs + 的灵敏度将流入电流识别为流入整流器K + （Kir）通道和Ca 2 + 通道或Cd 2 + 分别为20μm。当pHo从7.8降至6.8时，这两种电流均减小。还鉴定出谷氨酸（1 mm）激活的电流，半通道电流也因去除细胞外Ca 2 + 和施加1 mm奎尼丁而增强。谷氨酸激活电流和半通道电流均通过类似的pHo降低得到抑制。当所有这些抑制H + 的电流都被阻断时，随着pHo从7.8降低到6.8，一个小的，持续的内向电流在-60 mV时增加。另外，在该酸化过程中，-70和-20 mV之间的斜率电导增加。通过去除细胞外Na + 以及在ENa附近外推的Erev抑制H + 激活的电流，表明该电流主要由Na + < / sup>离子。

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