SCFA increase intestinal Na absorption by induction of NHE3 in rat colon and human intestinal C2/bbe cells

Short-chain fatty acids (SCFA), produced by colonic bacterial flora fermentation of dietary carbohydrates, promote colonic Na absorption through mechanisms not well understood. We hypothesized that SCFA promote increased expression of apical membrane Na/H exchange (NHE), serving as luminal physiolog...

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Published in:American journal of physiology: Gastrointestinal and liver physiology 2001-04, Vol.280 (4), p.G687-G693
Main Authors: Musch, M W, Bookstein, C, Xie, Y, Sellin, J H, Chang, E B
Format: Article
Language:English
Subjects:
Animals
Butyrates - pharmacology
Cells, Cultured
Colon - cytology
Colon - drug effects
Colon - enzymology
Dietary Fiber - pharmacology
Dose-Response Relationship, Drug
Enzyme Inhibitors - pharmacology
Fatty Acids, Volatile - pharmacology
Intestinal Absorption - drug effects
Intestinal Mucosa - drug effects
Intestinal Mucosa - enzymology
Intestines - cytology
Intestines - drug effects
Intestines - enzymology
Male
Microvilli - drug effects
Microvilli - enzymology
Microvilli - metabolism
Pectins - pharmacology
Rats
Sodium - metabolism
Sodium-Hydrogen Exchanger 3
Sodium-Hydrogen Exchangers - antagonists & inhibitors
Sodium-Hydrogen Exchangers - metabolism
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Summary:Short-chain fatty acids (SCFA), produced by colonic bacterial flora fermentation of dietary carbohydrates, promote colonic Na absorption through mechanisms not well understood. We hypothesized that SCFA promote increased expression of apical membrane Na/H exchange (NHE), serving as luminal physiological cues for regulating colonic Na absorptive capacity. Studies were performed in human colonic C2/bbe (C2) monolayers and in vivo. In C2 cells exposed to butyrate, acetate, proprionate, or the poorly metabolized SCFA isobutyrate, apical membrane NHE3 activity and protein expression increased in a time- and concentration-dependent manner, whereas no changes were observed for NHE2. In contrast, no significant changes in brush-border hydrolase or villin expression were noted. Analogous to the in vitro findings, rats fed the soluble fiber pectin exhibited a time-dependent increase in colonic NHE3, but not NHE2, protein, mRNA, and brush-border activity. These changes were region-specific, as no changes were observed in the ileum. We conclude that luminal SCFA are important physiological cues for regulating colonic Na absorptive function, allowing the colon to adapt to chronic changes in dietary carbohydrate and Na loads.
ISSN:0193-1857
1522-1547
DOI:10.1152/ajpgi.2001.280.4.G687