ACETATE ABSORPTION IN THE NORMAL AND SECRETING RAT JEJUNUM

Acetate absorption was studied in rat jejunum using steady state perfusion in vivo. Absorption conformed to apparent saturation kinetics and was similar in magnitude to glucose absorption. When compared with normal saline, acetate perfusion was associated with luminal alkalinisation. There was no difference in total CO2 secretion when similar rates of acetate and glucose absorption were compared, suggesting that total CO2 secretion was the result of mucosal metabolism. Absorption of acetate and propionate were mutually inhibitory. Acetate absorption was also inhibited by Tris-Hepes pH 7.0. When the gut was pretreated with cholera toxin to induce a secretory state, acetate absorption was reduced by 41.9%. This effect could be reproduced if similar water secretion was osmotically induced by the addition of mannitol. These data suggest that acetate is absorbed, at least, partially by non-ionic diffusion in the rat jejunum and that its absorption is reduced in the secreting intestine by solvent drag.