Apical K+ channels in Necturus taste cells. Modulation by intracellular factors and taste stimuli.
Apical K+ channels in Necturus taste cells. Modulation by intracellular factors and taste stimuli.
复制标题
除Necturus味道细胞中的顶端K+通道。细胞内因子和味觉刺激的调节。
DOI：
10.1085/jgp.99.4.591
复制
发表时间：
1992-04
影响因子：
3.8
通讯作者：
Kinnamon, S C
中科院分区：
文献类型：
--
作者：
Cummings, T A;Kinnamon, S C
利用膜片钳记录技术的细胞贴附、内向外和外向外配置，研究了Necturus味觉受体细胞的顶端受限、电压依赖的K+电导。在对称的K+溶液中，来自根尖膜的斑块通常包含许多电导为30至175ps的通道。通道密度如此之高，以至于只有在负电压下才能分辨出单一电流；在正电压下，膜片记录类似于全细胞记录。这些多通道斑块具有小但显著的静息电导，并被去极化强烈激活。膜片电流具有高度的K+选择性，其PK/PNa比值为28。随着时间的推移，允许根尖膜重新分布到基底外侧膜中，从而获得含有单个K+通道的斑块。分离观察到两种类型的K+通道。大电导Ca（2+）依赖性通道（135-175 pS）在细胞附着斑块中被强去极化激活，半激活电压约为-10 mV。在约-47 mV的半激活电压下，atp阻断的100 pS K+通道被弱去极化激活。所有的顶端K+通道都被柠檬酸直接施加于外向外和灌注的细胞贴附斑块的酸味刺激所阻断。苦味刺激奎宁直接作用时，通过改变通道门控降低打开概率，也阻断了所有通道。当奎宁在细胞外仅应用于膜片移液管外的膜和由内而外的膜片时，它会产生闪烁的块状物。因此，酸味和苦味刺激似乎通过不同的机制阻断相同的顶端K+通道，从而产生去极化受体电位。
The apically restricted, voltage-dependent K+ conductance of Necturus taste receptor cells was studied using cell-attached, inside-out and outside-out configurations of the patch-clamp recording technique. Patches from the apical membrane typically contained many channels with unitary conductances ranging from 30 to 175 pS in symmetrical K+ solutions. Channel density was so high that unitary currents could be resolved only at negative voltages; at positive voltages patch recordings resembled whole-cell recordings. These multi-channel patches had a small but significant resting conductance that was strongly activated by depolarization. Patch current was highly K+ selective, with a PK/PNa ratio of 28. Patches containing single K+ channels were obtained by allowing the apical membrane to redistribute into the basolateral membrane with time. Two types of K+ channels were observed in isolation. Ca(2+)-dependent channels of large conductance (135-175 pS) were activated in cell-attached patches by strong depolarization, with a half-activation voltage of approximately -10 mV. An ATP-blocked K+ channel of 100 pS was activated in cell-attached patches by weak depolarization, with a half-activation voltage of approximately -47 mV. All apical K+ channels were blocked by the sour taste stimulus citric acid directly applied to outside-out and perfused cell-attached patches. The bitter stimulus quinine also blocked all channels when applied directly by altering channel gating to reduce the open probability. When quinine was applied extracellularly only to the membrane outside the patch pipette and also to inside-out patches, it produced a flickery block. Thus, sour and bitter taste stimuli appear to block the same apical K+ channels via different mechanisms to produce depolarizing receptor potentials.