MALABSORPTION IN JOHNE'S DISEASE IN CATTLE: AN IN-VITRO STUDY OF L-HISTIDINE UPTAKE BY ISOLATED INTESTINAL TISSUE PREPARATIONS

Abstract

Rings of whole ileum or mucosal scrapings from clinical cases of Johne's disease, or from subclinically infected animals, accumulate L-histidine at considerably less than the normal rate when incubated in Krebs-Ringer bicarbonate solution containing this amino acid at a concentration of 20 mM. “ Active ” uptake of histidine against a concentration gradient can be abolished by the addition of 0·2 mM-2:4-dinitrophenol to the incubation medium. The proportion actively accumulated was about 61 per cent. in normal mucosal scrapings, but only some 25 per cent. in specimens obtained from clinically affected cattle.