Carbonic Anhydrase IV Mediates the Fizz of Carbonated Beverages

摘要

Humans perceive their environment through various sensory systems. While most of our senses including sight, hearing, touch, thermoception, and proprioception are tuned to the detection of physical events, the perception of smell and taste is induced by the activation of chemoreceptor cells in the nose and the oral cavity by volatile and nonvolatile molecules (tastants). Taste comprises five basic taste modalities, namely, bitter, sweet, sour, salty, and umami (savori-ness), and is mediated by the activation of taste receptor cells, which are assembled into taste buds distributed across different papillae on the tongue and palate epithelium. In the last decade, numerous genetic and functional studies revealed G-protein-coupled seven-transmembrane proteins as the chemoreceptors responding to sweet (hT1R2/ hT1R3), bitter (hT2Rs), and umami (hT1R1/hT1R3) stimuli, whereas the epithelial sodium channel (ENaC) and the transient receptor potential (TRP) ion channels PKD2L1 and PKD1L3 were suggested as receptor proteins for salty and sour taste, respectively. In addition, other types of oral sensations including cooling, pungency, tingling, and astrin-gency seem to be mediated independent of any specific receptor cell through free afferent nerve endings of neurons of the trigeminal nerve in the oral cavity.