2001年3月
Gramicidin-perforated patch analysis on HCO3- secretion through a forskolin-activated anion channel in rat parotid intralobular duct cells
JOURNAL OF MEMBRANE BIOLOGY
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- 巻
- 180
- 号
- 1
- 開始ページ
- 11
- 終了ページ
- 19
- 記述言語
- 英語
- 掲載種別
- DOI
- 10.1007/s002320010054
- 出版者・発行元
- SPRINGER-VERLAG
Forskolin-induced anion currents and depolarization were investigated to clarify the mechanism of HCO3- secretion in the intralobular duct cells of rat parotid glands. Anion currents of the cells were measured at the equilibrium potential of K+, using a gramicidin-perforated patch technique that negligibly affects intracellular anion concentration. The forskolin-induced anion current was sustained and significantly (54%) suppressed by glibenclamide (200 muM), a blocker of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel. The anion current was markedly suppressed by addition of 1 mM methazolamide, a carbonic anhydrase inhibitor, and removal of external HCO3-. Forskolin depolarized the cells in the current-clamp mode. Addition of methazolamide and removal of external HCO3- significantly decreased the depolarizing level. These results suggest that activation of anion channels (mainly the CFTR Cl- channel located in luminal membranes) and production of cytosolic HCO3- induce the inward anion current and resulting depolarization. Inhibition of the Na+-K+-2Cl(-) cotransporter and the Cl--HCO3- exchanger had no significant effect on the current or depolarization, indicating that the uptake of Cl- via the Na+-K+-2Cl(-) cotransporter or the Cl--HCO3- exchanger is not involved in the responses. Taken together, we conclude that forskolin activates the outward movement (probably secretion) of HCO3- produced intracellularly, but not of Cl- due to lack of active Cl- transport in parotid duct cells, and that the gramicidin-perforated patch method is very useful to analyze anion transport.
- リンク情報
- ID情報
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- DOI : 10.1007/s002320010054
- ISSN : 0022-2631
- Web of Science ID : WOS:000167375800002