Na+‐H+ exchange in sheep parotid endpieces

FEBS Letters

Poronnik, P.¹  Cook, D.I.¹  Young, J.A.¹ 

[1] Department of Physiology, University of Sydney, NSW 2006, Australia

关键词: Epithelial secretion;    Na+-H+ exchange;    BCECF;    Amiloride;    Sheep parotid gland;   

DOI  :  10.1016/0014-5793(93)81184-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have used microspectrofluorimetry with the pH-sensitive dye, BCECF, to examine the control of intracellular pH in the secretory endpieces of the sheep parotid gland. Unstimulated endpieces in HCO₃ ⁻-free media have a cytosolic pH of 7.5 ± 0.03 (n = 69) which is maintained by a Na⁺-dependent proton extrusion process that can be partially supported by Li⁺ but not by Cs⁺, and is not affected by changes in extracellular Cl⁻, HCO₃ ⁻ or K⁺. It is not blocked by SITS or DIDS, which inhibit Na⁺-(nHCO₃ ⁻ co-transport and Cl⁻¹-HCO₃ ⁻ exchange, nor is it sensitive to the amiloride analogs, MIA and EIPA, which inhibit Na⁺-H⁺ exchangers, although very high concentrations of amiloride itself (1 mmol/l) have a (probably non-specific) inhibitory effect. It seems likely that sheep parotid secretory endpieces do contain a Na⁺-H⁺ exchanger that drives secretion of a HCO₃ ⁻-rich juice, and that its insensitivity to amiloride and its analogs explains why these drugs do not block fluid secretion by the intact sheep parotid gland.

【 授权许可】

Unknown