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This Article Full Text Full Text (PDF) All Versions of this Article: 292/3/G711    most recent 00416.2006v1 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 HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Bachmann, O. Articles by Seidler, U. Search for Related Content PubMed PubMed Citation Articles by Bachmann, O. Articles by Seidler, U.

MUCOSAL BIOLOGY

Mechanisms of secretion-associated shrinkage and volume recovery in cultured rabbit parietal cells

¹Department of Gastroenterology, Hepatology, and Endocrinology, Hannover Medical School, Hannover, Germany; ²1st Department of Internal Medicine, Klinikum am Steinenberg, Reutlingen, and ³Institute of Anatomy, University of Tübingen, Tübingen, Germany

Submitted 8 September 2006 ; accepted in final form 2 November 2006

We have previously shown that stimulation of acid secretion in parietal cells causes rapid initial cell shrinkage, followed by Na⁺/H⁺ exchange-mediated regulatory volume increase (RVI). The factors leading to the initial cell shrinkage are unknown. We therefore monitored volume changes in cultured rabbit parietal cells by confocal measurement of the cytoplasmic calcein concentration. Although blocking the presumably apically located K⁺ channel KCNQ1 with chromanol 293b reduced both the forskolin- and carbachol-induced cell shrinkage, inhibition of Ca²⁺-sensitive K⁺ channels with charybdotoxin strongly inhibited the cell volume decrease after carbachol, but not after forskolin stimulation. The cell shrinkage induced by both secretagogues was partially inhibited by blocking H⁺-K⁺-ATPase with SCH28080 and completely absent after incubation with NPPB, which inhibits parietal cell anion conductances involved in acid secretion. The subsequent RVI was strongly inhibited with the Na⁺/H⁺ exchanger 1 (NHE1)-specific concentration of HOE642 and completely by 500 µM dimethyl-amiloride (DMA), which also inhibits NHE4. None of the above substances induced volume changes under baseline conditions. Our results indicate that cell volume decrease associated with acid secretion is dependent on the activation of K⁺ and Cl^– channels by the respective secretagogues. K⁺, Cl^–, and water secretion into the secretory canaliculi is thus one likely mechanism of stimulation-associated cell shrinkage in cultured parietal cells. The observed RVI is predominantly mediated by NHE1.

acid secretion; volume regulation; potassium channels; chloride channels

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