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Molecular mechanisms of transduction of gustatory stimuli in human and mammalian tatse cells.

人类和哺乳动物 tatse 细胞味觉刺激转导的分子机制。

基本信息

批准号：
05404063
负责人：
SATO Toshihide
金额：
$ 11.9万
依托单位：
Nagasaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

There are cation and anion channels on the receptive membrane of frog taste cells. Na^+ and Cl^- of NaCl stimuli pass through the cation channel and the anion channel, respectively. Since the Cl^- permeability is lower, a depolarization appears in the taste cell.We found 80 pS and 40 pS K^+ channels in the frog taste cell membranes. 80 pS K^+ channel in dependent on voltage and Ca^<2+>, but 40 pS K^+ channel is not. Closure of 40 pS K^+ channels is related to cAMP and protein kinase A.Both types of the K^+ channels exist densily on the receptive and dendritic membranes.Application of amiloride to the receptive membrane of a mouse taste cell within the taste bud produced an outward current, but application of it to the basolateral membrane did not. This suggests that amoloride-sensitive Na^+ channels exist mostly in the receptive membrane.There are two transduction pathways for sweet stimuli in gerbil taste cells. The gustatory transduction for sugars is concerned with a second messenger cAMP,but that for non-sugars like amino acids is concerned with IP_3.We have measured internal Ca^<2+> concentration in human taste buds of the fungiform papillae during taste stimulation. Different taste stimuli caused a change in Ca^<2+> concentration of different taste cells in the taste bud, indicating that each taste cell has differential chemical sensitivity.

蛙类味觉细胞受体膜上存在阳离子通道和阴离子通道。Na~+和Cl~-分别通过阳离子通道和阴离子通道。由于氯离子通透性较低，因此在青蛙味觉细胞膜上出现去极化现象。我们在青蛙味觉细胞膜上发现了80pS和40pS K+通道。80pS K^+通道依赖于电压和钙离子，而40pS K^+通道不依赖于电压和钙离子。40pS K~(++)通道的关闭与cAMP和蛋白激酶A有关，这两种K~(++)通道密集地存在于感受膜和树突膜上，阿米洛利作用于味蕾内小鼠味觉细胞的感受膜产生向外电流，而作用于基底膜则不产生外向电流。提示沙土鼠味觉细胞对甜味刺激有两条转导途径，即对阿莫洛利敏感的钠离子通道主要存在于感受膜上。糖的味觉转导与第二信使cAMP有关，而非糖类氨基酸的味觉转导与IP_3有关。我们测量了味觉刺激时人味蕾菌状乳头内钙离子的浓度。不同的味觉刺激引起味蕾中不同味觉细胞钙离子浓度的变化，说明不同的味觉细胞具有不同的化学敏感性。