Journal article

Publication year: 2021

Pages: 937-951

Journal: Pflügers Archiv European Journal of Physiology

Volume number: 473

Issue number: 6

ISSN: 0031-6768

eISSN: 1432-2013

Open access status: Hybrid

DOI Link: https://doi.org/10.1007/s00424-021-02565-8

Publisher: Springer

Abstract: 
Propionate, a metabolite from the microbial fermentation of carbohydrates, evokes a release of epithelial acetylcholine in rat caecum resulting in an increase of short-circuit current (I-sc) in Ussing chamber experiments. The present experiments were performed in order to characterize the ionic mechanisms underlying this response which has been thought to be due to Cl- secretion. As there are regional differences within the caecal epithelium, the experiments were conducted at oral and aboral rat corpus caeci. In both caecal segments, the propionate-induced I-sc (I-Prop) was inhibited by > 85%, when the experiments were performed either in nominally Cl-- or nominally HCO3--free buffer. In the case of Cl-, the dependency was restricted to the presence of Cl- in the serosal bath. Bumetanide, a blocker of the Na+-K+-2Cl(-)-cotransporter, only numerically reduced I-Prop suggesting that a large part of this current must be carried by an ion other than Cl-. In the aboral caecum, I-Prop was significantly inhibited by mucosally administered stilbene derivatives (SITS, DIDS, DNDS), which block anion exchangers. Serosal Na+-free buffer reduced I-Prop significantly in the oral (and numerically also in aboral) corpus caeci. RT-PCR experiments revealed the expression of several forms of Na+-dependent HCO3--cotransporters in caecum, which might underlie the observed Na+ dependency. These results suggest that propionate sensing in caecum is coupled to HCO3- secretion, which functionally would stabilize luminal pH when the microbial fermentation leads to an increase in the concentration of short-chain fatty acids in the caecal lumen.

Harvard Citation style: Ballout, J. and Diener, M. (2021) The role of HCO3– in propionate-induced anion secretion across rat caecal epithelium, Pflügers Archiv European Journal of Physiology, 473(6), pp. 937-951. https://doi.org/10.1007/s00424-021-02565-8

APA Citation style: Ballout, J., & Diener, M. (2021). The role of HCO3– in propionate-induced anion secretion across rat caecal epithelium. Pflügers Archiv European Journal of Physiology. 473(6), 937-951. https://doi.org/10.1007/s00424-021-02565-8