US EPA

5163345 

Journal Article 

Effects of extracellular pH, PCO2, and HCO3- on intracellular pH in isolated rat taste buds 

Lyall, V; Feldman, GM; Heck, GL; Desimone, JA 

1997 

Yes 

American Journal of Physiology
ISSN: 0002-9513
EISSN: 2163-5773 

273 

3 Pt 1 

C1008-C1019 

English 

9316422 

10.1152/ajpcell.1997.273.3.C1008 

WOS:A1997XV71000027 

We studied the effects of changing external pH (pHo), external bicarbonate concentration ([HCO3-]o), and PCO2 on taste receptor cell (TRC) intracellular pH (pHi) in taste bud fragments (TBFs) isolated from rat circumvallate and fungiform papillae with the pH-sensitive fluoroprobe 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) using microfluorometric and imaging techniques. In N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid-buffered solutions, TRC pHi responded rapidly and monotonically to changes in pHo between 6.5 and 8.0. The relationship between pHi and pHo was steep, with slopes varying between 0.8 and 1.2. Similarly, varying pHo by changing PCO2 at constant [HCO3-]o or changing [HCO3-]o at constant PCO2 led to rapid, monotonic changes in pHi. The relationship between pHi and pHo was once again steep, with slopes varying between 0.8 and 1.2. However, simultaneous changes in PCO2 and [HCO3-]o at constant pHo did not cause any significant changes in steady-state pHi. In imaging studies, single, isolated TRCs responded to changes in pHo, with parallel changes in pHi in the soma and apical process. In addition, changes in pHo induced parallel changes in pHi throughout TBFs. These data suggest that the steady-state TRC pHi is a function of pHo. Changes in TRC pHi may be involved in acid sensing, and salivary [HCO3-] may play a role in the maintainance of steady-state TRC pHi and in the neutralization of acid-induced changes in pHi. 

2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein microfluorometry; epifluoresence microscope; circumvallate papillae; fungiform papillae