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Updated: Jan 8, 2026

In Vitro Characterization of the Electrophysiological Properties of Colonic Afferent Fibers in Rats
Published on: September 27, 2017
Short-chain fatty acids decrease the frequency of spontaneous contractions of longitudinal muscle via enteric nerves
Shigeyuki Ono1, Shin-ichiro Karaki, Atsukazu Kuwahara
1Laboratory of Physiology, Graduate School of Nutritional and Environmental Sciences, Institute for Environmental Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
Abstract:
Short-chain fatty acids (SCFAs) produced by the bacterial fermentation of carbohydrates in the cecum and proximal colon are reported to modify colonic motility as a luminal factor. Besides the physical stimuli in the distal colon, SCFAs in the intestinal lumen also seem to affect colonic motility under physiological concentrations. This study therefore used fasted rats to investigate the effect of SCFAs on the spontaneous contractions of longitudinal muscle (LM) in rat distal colon, including mucosa in vitro. The frequency of spontaneous contractions of LM strips from the distal colon was 9.4 +/- 0.5 contractions/20 min. The exogenous addition of >5 mM SCFAs decreased the frequency of spontaneous contractions of the LM to 6.1 +/- 0.8 contractions/20 min. Among SCFAs, only acetate elicited this inhibitory response. TTX and the combination of hexamethonium and granisetron abolished SCFA-induced inhibitory response, suggesting that this inhibitory response is mediated via the ENS, including nicotinic and 5-HT(3) receptors. In conclusion, it is suggested that SCFAs in rat distal colon decrease the frequency of spontaneous contractions of the LM and that SCFAs may contribute to colonic motility, including the peristaltic reflex, by regulating the frequency of spontaneous contractions of the LM through the enteric nervous system (ENS).
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