A stimulus-activated conductance in isolated taste epithelial membranes.
A stimulus-activated conductance in isolated taste epithelial membranes.
复制标题
孤立的味觉上皮膜中的刺激激活电导。
DOI：
10.1016/s0006-3495(90)82370-5
复制
发表时间：
1990
影响因子：
3.4
通讯作者：
Kumazawa,T
中科院分区：
文献类型：
--
作者：
Teeter,JH;Brand,JG;Kumazawa,T
从鲶鱼的皮肤味觉上皮细胞分离的膜泡被纳入到贴片移液器的尖端上的磷脂双层中。在大约50%的双层中观察到电压依赖性电导，并记录了电导从8到大于250 pS的单通道电流。在40%的双层显示没有电压依赖性电导，微摩尔浓度的L-精氨酸，一个有力的刺激一类鲶鱼氨基酸味觉受体，激活非选择性阳离子电导。L-精氨酸门控电导是浓度依赖性的，显示响应于约15 μ M L-精氨酸的半最大激活。L-精氨酸激活的通道具有40-50 pS的单位电导，并且在移液管中的假细胞内溶液和浴中的林格氏溶液的情况下在-6和+18 mV之间逆转。L-丙氨酸，一个有效的刺激其他主要类别的鲶鱼氨基酸味觉受体，没有改变双层电导。D-精氨酸，这是一个相对无效的味道刺激鲶鱼，但一个很好的交叉适配器的L-精氨酸诱导的神经反应，在浓度低于200 μ M的双层电导没有影响。然而，D-精氨酸浓度从1 μ M增加到100 μ M，逐渐抑制L-精氨酸激活的电导，这表明D-精氨酸竞争L-精氨酸受体，但不激活相关的阳离子通道。这一解释与最近在该系统中的生物化学结合研究相一致。这些结果表明，L-精氨酸味觉受体蛋白在鲶鱼的一部分，或密切耦合到阳离子选择性通道，这是开放的L-精氨酸结合。
Membrane vesicles isolated from the cutaneous taste epithelium of the catfish were incorporated into phospholipid bilayers on the tips of patch pipettes. Voltage-dependent conductances were observed in approximately 50% of the bilayers and single-channel currents having conductances from 8 to greater than 250 pS were recorded. In 40% of the bilayers displaying no voltage-dependent conductances, micromolar concentrations of L-arginine, a potent stimulus for one class of catfish amino acid taste receptors, activated a nonselective cation conductance. The L-arginine-gated conductance was concentration-dependent, showing half-maximal activation in response to approximately 15 microM L-arginine. L-Arginine-activated channels had unitary conductances of 40–50 pS and reversed between -6 and +18 mV with pseudointracellular solution in the pipette and Ringer in the bath. L-Alanine, a potent stimulus for the other major class of catfish amino acid taste receptors, did not alter bilayer conductance. D-Arginine, which is a relatively ineffective taste stimulus for catfish but a good cross-adapter of the L-arginine-induced neural response, had no effect on bilayer conductance at concentrations below 200 microM. However, increasing concentrations of D-arginine from 1 to 100 microM progressively suppressed the L-arginine-activated conductance, suggesting that D-arginine competed for the L-arginine receptor, but did not activate the associated cation channel. This interpretation is consonant with recent biochemical binding studies in this system. These results suggest that L-arginine taste receptor proteins in the catfish are part of or closely coupled to cation-selective channels which are opened by L-arginine binding.