Bicarbonate ion transport by the electrogenic Na+ /HCO3- cotransporter, NBCe1, is required for normal electrical slow-wave activity in mouse small intestine.
Neurogastroenterol Motil
; 33(9): e14149, 2021 09.
Article
em En
| MEDLINE
| ID: mdl-33837991
ABSTRACT
BACKGROUND:
Normal gastrointestinal motility depends on electrical slow-wave activity generated by interstitial cells of Cajal (ICC) in the tunica muscularis of the gastrointestinal tract. A requirement for HCO3- in extracellular solutions used to record slow waves indicates a role for HCO3- transport in ICC pacemaking. The Slc4a4 gene transcript encoding the electrogenic Na+ /HCO3- cotransporter, NBCe1, is enriched in mouse small intestinal myenteric region ICC (ICC-MY) that generate slow waves. This study aimed to determine how extracellular HCO3- concentrations affect electrical activity in mouse small intestine and to determine the contribution of NBCe1 activity to these effects.METHODS:
Immunohistochemistry and sharp electrode electrical recordings were used. KEYRESULTS:
The NBCe1 immunoreactivity was localized to ICC-MY of the tunica muscularis. In sharp electrode electrical recordings, removal of HCO3- from extracellular solutions caused significant, reversible, depolarization of the smooth muscle and a reduction in slow-wave amplitude and frequency. In 100 mM HCO3- , the muscle hyperpolarized and slow wave amplitude and frequency increased. The effects of replacing extracellular Na+ with Li+ , an ion that does not support NBCe1 activity, were similar to, but larger than, the effects of removing HCO3- . There were no additional changes to electrical activity when HCO3- was removed from Li+ containing solutions. The Na+ /HCO3- cotransport inhibitor, S-0859 (30µM) significantly reduced the effect of removing HCO3- on electrical activity. CONCLUSIONS & INFERENCES These studies demonstrate a major role for Na+ /HCO3- cotransport by NBCe1 in electrical activity of mouse small intestine and indicated that regulation of intracellular acidbase homeostasis contributes to generation of normal pacemaker activity in the gastrointestinal tract.Palavras-chave
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Bicarbonatos
/
Simportadores de Sódio-Bicarbonato
/
Motilidade Gastrointestinal
/
Intestino Delgado
Limite:
Animals
Idioma:
En
Revista:
Neurogastroenterol Motil
Ano de publicação:
2021
Tipo de documento:
Article