AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 4 547-R553, Copyright © 1992 by American Physiological Society

ARTICLES

Vertebrate gastrointestinal fermentation: transport mechanisms for volatile fatty acids

E. Titus and G. A. Ahearn
Department of Zoology, University of Hawaii, Manoa, Honolulu 96822.

Symbiotic microbial fermentation of plant polysaccharides can potentially provide significant levels of nutrients to host organisms in the form of volatile fatty acids (VFAs). Microbial fermentation can account for as much as 10% of maintenance energy requirements in carnivores and omnivores, and up to 80% in ruminant herbivores. In this review epithelial transport processes for the products of microbial fermentation are described in various mammalian and lower vertebrate species. Studies of transepithelial movement of VFA in vertebrate gastrointestinal systems have mostly been investigated in the mammals. In these it is widely held that the transmural movement of VFA is a concentration-dependent passive diffusion process whereby VFA is transported in the protonated form. A different model is described in this paper for carrier-mediated VFA transport, by way of anionic exchange with intracellular bicarbonate, in the intestine of a fermenting herbivorous teleost. These models for diffusive and carrier-mediated transport are compared and discussed from both physiological and experimental viewpoints.

This article has been cited by other articles:

				J. R. Aschenbach, S. K. Bhatia, H. Pfannkuche, and G. Gabel Glucose Is Absorbed in a Sodium-Dependent Manner from Forestomach Contents of Sheep J. Nutr., November 1, 2000; 130(11): 2797 - 2801. [Abstract] [Full Text] [PDF]

				C. E. STEVENS and I. D. HUME Contributions of Microbes in Vertebrate Gastrointestinal Tract to Production and Conservation of Nutrients Physiol Rev, April 1, 1998; 78(2): 393 - 427. [Abstract] [Full Text] [PDF]