Serosal application of Ba2+ induces oscillatory chloride secretion via activation of submucosal cholinergic neurones in guinea-pig distal colon

Mariko Nishikitani, A. Kokubo, H. Takemura, K. Saigenji, K. Kawahara

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The enteric nervous system regulates ion and fluid secretion in the mammalian intestine at both resting and stimulated conditions. To determine the type and activation mechanism of neurones involved, mucosa-submucosa sheets isolated from guinea-pig distal colon were studied in vitro in Ussing chambers. Serosal addition of 0.5-1 mM barium (Ba2+), a potassium (K+) channel inhibitor, caused oscillatory increases in short-circuit current (/sc). Mean values of the size and frequency of /sc were 369. 1 μA cm-2 and 2.3 min-1. The oscillatory /sc induced by the low concentrations of Ba2+ was blocked by either higher concentrations of Ba2+ (2-5 mM) or other K+ channel inhibitors, such as tetraethylammonium (TEA) (1 mM) and quinine (20 mM). The Ba2+-induced oscillatory /sc was also inhibited by tetrodotoxin (TTX) and atropine. In a nominally Ca2+ free solution plus serosal addition of 0.1 mM ethylene glycol-bis (β-aminoethyl ether) N, N, N′, N′-tetraacetic acid (EGTA), a Ca2+ chelator, the oscillatory /sc slowed and diminished. Further, the Ba2+-induced oscillatory /sc was partially inhibited by apical addition of 100 μM 5′-nitro-2-(3-phenylpropylamino)benzoic-acid (NPPB), a Cl- channel inhibitor, and completely disappeared in a low Cl- solution (11 mM) on both sides. On the other hand, application of either cimetidine, a histamine H2 receptor antagonist, or hexamethonium, a nicotinic antagonist, to the serosal side did not affect the Ba2+-induced oscillatory /sc. In conclusion, the Ba2+-induced oscillatory /sc is the transepithelial Cl- current which is stimulated by activation of cholinergic neurones in submucosal plexus of guinea-pig distal colon.

Original languageEnglish
Pages (from-to)257-264
Number of pages8
JournalActa Physiologica Scandinavica
Volume174
Issue number3
DOIs
Publication statusPublished - Jan 1 2002
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physiology

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