HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 293/4/G824    most recent 00125.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Shimamoto, C. Articles by Nakahari, T. Search for Related Content PubMed PubMed Citation Articles by Shimamoto, C. Articles by Nakahari, T.

MUCOSAL BIOLOGY

[Cl^–]_i modulation of Ca²⁺-regulated exocytosis in ACh-stimulated antral mucous cells of guinea pig

¹Central Research Laboratory (Nakahari Project), ²Department of Internal Medicine (Division II), and ³Department of Physiology, Osaka Medical College, Takatsuki, Japan

Submitted 13 March 2007 ; accepted in final form 1 August 2007

The effects of intracellular Cl^– concentration ([Cl^–]_i) on acetylcholine (ACh)-stimulated exocytosis were studied in guinea pig antral mucous cells by video microscopy. ACh activated Ca²⁺-regulated exocytosis (an initial phase followed by a sustained phase). Bumetanide (20 µM) or a Cl^– -free (NO₃^–) solution enhanced it; in contrast, 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB, a Cl^– channel blocker) decreased it and eliminated the enhancement induced by bumetanide or NO₃^– solution. ACh and Ca²⁺ dose-response studies demonstrated that NO₃^– solution does not shift their dose-response curves, and ATP depletion studies by dinitrophenol or anoxia demonstrated that exposure of NO₃^– solution prior to ATP depletion induced an enhanced initial phase followed by a sustained phase, whereas exposure of NO₃^– solution after ATP depletion induced only a sustained phase. Intracellular Ca²⁺ concentration ([Ca²⁺]_i) measurements showed that bumetanide and NO₃^– solution enhanced the ACh-stimulated [Ca²⁺]_i increase. Measurements of [Cl^–]_i revealed that ACh decreases [Cl^–]_i and that bumetanide and NO₃^– solution decreased [Cl^–]_i and enhanced the ACh-evoked [Cl^–]_i decrease; in contrast, NPPB increased [Cl^–]_i and inhibited the [Cl^–]_i decrease induced by ACh, bumetanide, or NO₃^– solution. These suggest that [Cl^–]_i modulates [Ca²⁺]_i increase and ATP-dependent priming. In conclusion, a decrease in [Cl^–]_i accelerates ATP-dependent priming and [Ca²⁺]_i increase, which enhance Ca²⁺-regulated exocytosis in ACh-stimulated antral mucous cells.

gastric antrum; mucin exocytosis; acetylcholine; intracellular Cl^– concentration