Garcia MAS, Yang N, Quinton PM. Normal mouse intestinal mucus release requires cystic fibrosis transmembrane regulator-dependent bicarbonate secretion.
J Clin Invest 2009;
119:2613-22. [PMID:
19726884 DOI:
10.1172/jci38662]
[Citation(s) in RCA: 217] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 07/01/2009] [Indexed: 12/16/2022] Open
Abstract
The mechanisms underlying mucus-associated pathologies in cystic fibrosis (CF) remain obscure. However, recent studies indicate that CF transmembrane conductance regulator (CFTR) is required for bicarbonate (HCO3-) transport and that HCO3- is critical for normal mucus formation. We therefore investigated the role of HCO3- in mucus secretion using mouse small intestine segments ex vivo. Basal rates of mucus release in the presence or absence of HCO3- were similar. However, in the absence of HCO3-, mucus release stimulated by either PGE2 or 5-hydroxytryptamine (5-HT) was approximately half that stimulated by these molecules in the presence of HCO3-. Inhibition of HCO3- and fluid transport markedly reduced stimulated mucus release. However, neither absence of HCO3- nor inhibition of HCO3- transport affected fluid secretion rates, indicating that the effect of HCO3- removal on mucus release was not due to decreased fluid secretion. In a mouse model of CF (mice homozygous for the most common human CFTR mutation), intestinal mucus release was minimal when stimulated with either PGE2 or 5-HT in the presence or absence of HCO3-. These data suggest that normal mucus release requires concurrent HCO3- secretion and that the characteristically aggregated mucus observed in mucin-secreting organs in individuals with CF may be a consequence of defective HCO3- transport.
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