摘要
Among the five basic taste modalities, sourness refers to our ability to detect acids within food. It not only helps us to maintain the acid-base balance and avoid the bad resources, but also provides us satisfying feelings during eating. Both human psychophysical and animal behavioral results demonstrated that sour sensation is elicited by protons dissociated from acids as well as by undissociated acid molecules. In peripheral taste organs, acids are detected by a population of taste receptor cells that express the trp channel PKD2L1; however, the cellular and molecular mechanisms of sour sensation are not clear yet. One problem in many previous studies is that sour-sensing cells were not distinguished from other populations of taste cells. Here by using BAC transgenic mice in which the sour-sensing taste cells were genetically labeled with YFP, we show that action potentials are evoked directly in PKD2L1-expressing sour-sensing taste cells by extracellular protons. This response to dissociated protons is driven by proton entry through a proton-selective conductance specifically expressed on the apical surface of these cells. Moreover, we show that undissociated weak acids evoke action potentials directly in PKD2L1-YFP taste cells as well. The response to weak acids is unlikely to be a consequence of inhibiting K + channels by intracellular protons, as previously thought, but can be possibly attributed to the activation of voltage-gated Na+ channels. Together, we conclude that both protons and undissociated acid molecules elicit sour sensations by activating PKD2L1-expressing taste cells, but through different cellular mechanisms.
摘要译文
在五个基本味觉方式，酸味是指我们的食品检测中的酸的能力。它不仅可以帮助我们维持酸碱平衡，避免坏的资源，而且还吃期间为我们提供满意的感受。人类心理物理和动物行为的结果表明，酸味感觉是引起由酸以及由未电离酸分子的质子解离。在外围味觉器官，酸是由味觉受体细胞表达的TRP通道PKD2L1群检测;然而，酸感的细胞和分子机制尚不清楚。在许多以前的研究的一个问题是酸感应细胞没有从味细胞的其他人群区分开来。这里使用的BAC转基因小鼠，其中酸味感味道细胞遗传标记YFP，我们表明，动作电位是直接在PKD2L1表达酸味传感味觉细胞通过细胞外质子诱发。这响应于解离的质子是通过对这些细胞的顶端表面特异性表达的质子选择性电导质子条目驱动。此外，我们表明，未离解的弱酸直接在PKD2L1-YFP的味觉细胞唤起动作电位为好。弱酸的反应不太可能是抑制K +通道通过细胞内的质子的一个结果，如以前认为，但可以有可能归因于电压门控Na +通道的活化。总之，我们的结论是既质子和未解离的酸分子通过激活PKD2L1表达味觉细胞引起酸的感觉，但是通过不同的细胞机制。
Chang, Rui. Cellular mechanisms of sour taste[D]. US: University of Southern California, 2011