Absorption of Volatile Fatty Acids from the Cecum of Sheep

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Abstract
A simple surgical procedure was developed in which the cecal lumen was isolated and a cannula implanted which enabled the rapid quantitative addition and removal of volatile fatty acid (VFA) solutions to and from the cecum of conscious sheep. The absorption rates of acetate, propionate and butyrate, as determined by the disappearance of VFA from the cecum, were altered by experimental procedures. The rate of absorption of individual VFA was decreased by increasing the pH from 6.2 to 7.5 and by increasing the osmolarity within the cecum but was not influenced by the presence of other VFA. The absorption rate was increased by increasing the concentration difference. Data indicate that the absorption process does not occur against a concentration difference, does not require cellular energy and is not saturated at VFA concentrations of eight times their physiological level. Thus, the absorption of VFA from the cecum does not occur by active transport and appears to be primarily by simple diffusion. However, the possibility of a carrier-mediated diffusion was not eliminated. The surgical implantation of the cecal cannula provided a very satisfactory technique to study VFA absorption and could be profitably used for a wide variety of in vivo digestion and absorption studies. Copyright © 1967. American Society of Animal Science . Copyright 1967 by American Society of Animal Science