The absorption of amino acids from the rumen of the sheep. II. The transfer of histidine, glycine, and ammonia across the rumen epithelium in vitro

Abstract

The transfer of L-histidine, glycine, and ammonia across the rumen epithelium of sheep was determined with in vitro preparations. The transfer of L-histidine and glycine was less than that of ammonia, but the transfer of L-histidine, glycine, and ammonia increased with increasing concentration. The transfer of L-histidine across the epithelium was unidirectional and specific for L-histidine, and was reduced by the presence of 2,4-dinitrophenol and iodoacetate and the presence of other amino acids in the test solution. Less than 5 % of the L-histidine and glycine was metabolized by the rumen epithelium. Starvation of the sheep prior to slaughter resulted in a twofold increase in the transfer of L-histidine and glycine across the rumen epithelium and no change in the transfer of ammonia.