Active Transport of Glycine by Rumen Epithelium of Betal Goats

Open Access
Publisher Website
Google Scholar
Abstract
Glyeine transport by in vitro preparation of rumen epithelium of betal goats was stud- ied. Transport of glyeine across the ru- men epithelium and its accumulation inside cell took place against the chemical gradi- ent suggestive of active transport, involv- ing cellular metabolism. The participation of cellular metabolism in this process was also conceived from the observed inhibitory effect on the process by 2,4-dinitrophenol and iodoacetate, the common metabolic inhibitors. The incubation medium was Krebs Ringer-bicarbonate saline alone or containing 50 t~( of 2,4-dinitrophenol or 16.1 m~ of iodoacetic acid. The amino acids, either dietary or produced de novo by the rumen microflora were consid- ered to be used chiefly for protein synthesis by the tureen microorganisms. These proteins are broken down by the proteinases in the gastro- intestinal tract and the released amino acids are absorbed. The transport of amino acids through the rumen in sheep was determined by Annison (1) by the difference of alpha amino N concentration in the blood entering and leav- ing the rumen. No significant difference was obtained and the importance of rumen in con- nection with amino acid absorption remained unsubstantiated. Cook et al. (3), however, re- investigated the phenomenon by putting pure amino acids, including glycine, in the rumen of steer and following the increase in blood amino acid concentration. These studies, though informative in the sense that the rumen might function as an important absorptive organ for amino acids apart from fatty acids, did not re- veal the nature of such transport. The observed phenomenon may be a passive one, due to in- creased concentration of amino acid in rumen fluid (Cook et al. used 5 to 10 g glycine) or might involve the epithelial activity. It was our objective to investigate in more detail the uptake of the amino acid glycine, using in vitro preparations of rumen and the effect of added 2,4-dinitrophenol (DNP) and iodoacetate as the usual metabolic inhibitors.