Passive and active membrane properties of mudpuppy taste receptor cells.
Passive and active membrane properties of mudpuppy taste receptor cells.
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泥巴犬味觉受体细胞的被动和主动膜特性。
DOI：
10.1113/jphysiol.1987.sp016431
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Roper,SD
中科院分区：
文献类型：
--
作者：
Kinnamon,SC;Roper,SD
1.细胞内记录从味觉感受器细胞和表面上皮细胞的分离mudpuppy舌上皮。2.表面上皮细胞的平均静息电位为-40.2 +/-8.9 mV，平均输入电阻为40.3 +/-11.3 M Ω，电流-电压（I-V）关系呈线性。味觉感受器细胞的平均静息电位为-61.7 +/-15 mV，平均输入电阻为380.3 +/-177.2 M Ω，I-V关系显示出明显的外向整流;外向整流在高K+盐水中持续存在，但被溴化四乙基铵（TEA）消除。3.表面上皮细胞对去极化电流的反应只有被动的膜电位变化。味觉感受器细胞对去极化电流注入的短暂脉冲作出反应，其再生动作电位的特征在于突然上升相，下降相的持续时间和延长的后电位。4.河豚毒素（TTX）阻断了动作电位的突然上升相，表明电压门控Na+电流负责上升相。5.用TEA阻断外向K+电流和TTX阻断Na+电流处理的细胞，以及浸泡在等渗CaCl 2中的细胞，可引发长持续时间动作电位。这些结果表明，主动膜反应包含一个显着的Ca 2+成分。6.通过向浴槽培养基中加入Ca 2+通道阻断剂，后电位被阻断或大大降低。相比之下，将TEA添加到浴槽介质中大大增强了后电位。这些数据表明，后电位的很大一部分是Ca 2+介导的。7.后电位的平均逆转电位（-76.8 +/-6.0 mV）与动作电位下冲的平均逆转电位（-86 +/-5.6 mV）显著不同。用TEA灌注将后电位的逆转电位降低至-42.3 +/-8.2 mV，并消除了下冲。这些结果表明，后电位由至少两个电导引起，一个电导被TEA阻断，另一个电导依赖于Ca 2+，并且涉及K+以外的离子或除K+之外的离子。8.我们的数据表明，与表面上皮细胞不同，味觉受体细胞具有电压门控Na+，Ca 2+和K+通道，以及Ca 2+介导的通道。Ca ~（2+）通道的作用可能部分是调节递质释放到神经末梢。其他电导在味觉传导中的作用尚不清楚。
1. Intracellular recordings were obtained from taste receptor cells and surface epithelial cells of isolated mudpuppy lingual epithelium. 2. Surface epithelial cells had a mean resting potential of ‐40.2 +/‐ 8.9 mV, a mean input resistance of 40.3 +/‐ 11.3 M omega, and a linear current‐voltage (I‐V) relationship. Taste receptor cells had a mean resting potential of ‐61.7 +/‐ 15 mV, a mean input resistance of 380.3 +/‐ 177.2 M omega, and the I‐V relationship showed pronounced outward rectification; the outward rectification persisted in high‐K+ saline, but was abolished by tetraethylammonium bromide (TEA). 3. Surface epithelial cells responded to depolarizing current injection with only passive membrane potential changes. Taste receptor cells responded to brief pulses of depolarizing current injection with regenerative action potentials characterized by an abrupt rising phase, an inflexion on the falling phase, and a prolonged after‐potential. 4. The abrupt rising phase of the action potential was blocked by tetrodotoxin (TTX), suggesting that voltage‐gated Na+ currents are responsible for the rising phase. 5. Long‐duration action potentials were elicited from cells treated with TEA to block outward K+ currents and with TTX to block Na+ currents, and from cells bathed in isotonic CaCl2. These results suggest that the active membrane response contains a significant Ca2+ component. 6. The after‐potential was blocked or greatly reduced by the addition of Ca2+ channel blockers to the bathing medium. In contrast, addition of TEA to the bathing medium greatly enhanced the after‐potential. These data suggest that a significant portion of the after‐potential is Ca2+ mediated. 7. The mean reversal potential for the after‐potential (‐76.8 +/‐ 6.0 mV) was significantly different from the mean reversal potential for the undershoot of the action potential (‐86 +/‐ 5.6 mV). Superfusion with TEA reduced the reversal potential of the after‐potential to ‐42.3 +/‐ 8.2 mV and abolished the undershoot. These results suggest that the after‐potential results from at least two conductances, one which is blocked by TEA and the other which is Ca2+ dependent and involves ions other than, or in addition to K+. 8. Our data suggest that taste receptor cells, unlike surface epithelial cells, possess voltage‐gated Na+, Ca2+, and K+ channels, as well as Ca2+‐mediated channels. The role of the Ca2+ channels may be in part to regulate release of transmitter onto nerve terminals. The role of the other conductances in taste transduction is unknown.