The metabolism of short-chain fatty acids in the sheep. 5. Some interrelationships in the metabolism of fatty acids and glucose by sheep-rumen epithelial tissue

Functional development of epithelial tissue of the reticulo-rumen in calves

“…Kiddle et al (1951) came to the same conclusion from other, less strong evidence. Support for this theory came from Pennington (1952) who showed In In vitro incubation studies that rumen epithelium could metabolize the VFA in the order butyrate > propionate > acetate. Thus the most valid measurements of absorption rates would appear to be those using disappearance of VFA from the rumen contents as their main criterion.…”

“…1955Seto et al. , 1956) one would expect intermediates of this cycle to be anti-ketogenie also, yet the opposite has been demon strated (Pennington and Sutherland, 1956a;Seto et al, 1955).…”

“…More recent studies suggested this theory may no longer be valid. There is strong evidence (Pennington, 1952;Seto et al, 1955) It is likely that the metabolism of VFA will affect the con centration gradients and, since the rate of metabolism is different for each acid, the concentration gradients will be affected unequally. One cannot therefore assume, as did Danlelll et al, that the different specific absorption rates of the VFA reflect primarily the nature of the membrane sep arating the rumen contents from the blood.…”

“…1951;Masson and Phillipson, 1951) that certain appar ent anomalies in their absorption studies might be explained by metabolism of butyrate and perhaps propionate by rumen epithelium led to the extensive investigations of Pennington and later to those of Seto and his group in Japan. Pennington (1952) and Seto .et al (1955) showed that rumen epithelium incubated in vitro metabolized VFA in the order butyrate > propionate > acetate. Of several other tissues studied, only epithelium from the reticulum and omasum, and liver tissue had a similar affinity for butyrate.…”

“…Pro pionate apparently fixes carbon dioxide to form succinate; by this means it can enter the tricarboxylic acid cycle and so be metabolized. The tricarboxylic acid cycle is active in rumen epithelium (Pennington, 1954;Pennington and Sutherland, 1956a;Seto and Umezu, 1959), but its significance is still not clear. The addition of compounds known to inhibit the tricarboxylic acid cycle has little effect on acetate or butyrate uptake by epithelium (Seto et al, 1957).…”