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The mechanism of taste reception of morphological indentified cells in the frog taste disc

青蛙味盘形态识别细胞的味觉接收机制

基本信息

批准号：
17591947
负责人：
KITADA Yasuyuki
金额：
$ 2.24万
依托单位：
Iwate Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

项目摘要

To investigate the mechanism of taste reception in taste cells, we used patch-clamp and Ca^<2+> imaging technique. In vertical slices of the bullfrog (Rana catesbeiana) taste disc, cell types were identified by staining with Alexa Fluor in a pipette. Calcium Green-1 Dextran (CaGD), a fluorescent Ca^<2+> indicator, was also added to the patch pipette. Lingual slices containing CaDG-labeled taste cells were imaged with a scanning confocal microscoe. Focal chemical stimulation was applied to the apical end of the taste disc. Focal bitter (quinine) stimulation induced an increase in membrane current and an increase in intracellular Ca^<2+> in type Ib and type II cells. In Ca^<2+> free bath solution, an increase in intracellular Ca^<2+> induced by bitter stimulation was observed in type Ib and type II cells. This suggests that focal bitter stimulation induce release of Ca^<2+> from internal stores. Focal Ca^<2+> (or Na^+) stimulation also induced an increase in membrane current and an increase in intracellular Ca^<2+> only in type III cells. Depolarization with high K^+ external solution induced an increase in intracellular Ca^<2+> only in type III cells. Therefore, an increase in intracellular Ca^<2+> in type III cells may be due to external Ca^<2+> via voltage- gated Ca^<2+> channels. The present results suggest that type Ib and type II cells are bitter-taste receptor cells and that type III cells are salt-taste receptor cells.

为了研究味觉细胞的味觉接收机制，我们采用膜片钳和Ca^<2+>成像技术。在牛蛙（Rana catesbeiana）味觉盘的垂直切片中，通过在移液管中用Alexa Fluor染色来鉴定细胞类型。钙绿-1葡聚糖（CaGD），一种荧光Ca^<2+>指示剂，也加入到贴片移液管中。用扫描共聚焦显微镜对含有cadg标记的味觉细胞的舌片进行成像。在味觉盘的顶端施加局部化学刺激。局部苦味（奎宁）刺激诱导Ib型和II型细胞的膜电流增加和细胞内Ca^<2+>增加。在无Ca^<2+>溶液中，苦味刺激诱导Ib和II型细胞内Ca^<2+>升高。这表明局部苦味刺激诱导Ca^<2+>从内部储存释放。局部Ca^<2+>（或Na^+）刺激也仅在III型细胞中诱导膜电流增加和细胞内Ca^<2+>增加。高K^+外溶液去极化仅在III型细胞中引起细胞内Ca^<2+>的增加。因此，III型细胞内Ca^<2+>的增加可能是由于通过电压门控Ca^<2+>通道的外部Ca^<2+>。结果表明，Ib型和II型细胞为苦味受体细胞，III型细胞为咸味受体细胞。