Intestinal absorption of sugars and amino acids in the earthworm

Absorption of glucose, galactose, fructose and leucine from luminal to coelomic compartments across the intestinal wall of Scherotheca sp. seems to be a simple diffusion process and not a product of active transport or facilitated diffusion. A concentration gradient never developed from identical initial concentrations of the 14C-labelled substrates on either side of in vitro everted intestinal sacs. The rates of net passage of glucose and galactose were in linear function with the respective sugar concentration gradient. A competition between these two sugars was not observed. The diffusion rate of glucose was higher from mucosal to serosal than in reverse direction. Intestinal tissues synthesized glycogen from glucose in the medium, this process being strongly inhibited by dinitrophenol.