Influence of Dietary Electrolytes on Lysine and Arginine Absorption in Chick Intestine

Abstract

The intestinal absorption of lysine and arginine in the chick was characterized using an in situ- ligated intestinal segment technique, and the influence of dietary electrolytes on their absorption was examined. Each amino acid, labeled with 14 C and provided at a concentration of .5 mM, was introduced into the lumen of the small intestine of young chicks. Absorption was defined as disappearance of label from the lumen after 4 min.Lysine absorption was greater than arginine absorption in the duodenum and in the middle and distal small intestine. The Jmax values for absorption of lysine and arginine were 315.0 nmol/min and 112.0 nmol/min, whereas the respective Kt values were 2.3 mM and 2.0 mM. Maximal transport of lysine and arginine occurred at pH 6.0. Lysine absorption was depressed (P<.05) at pH 5.0 and pH 8.0, whereas arginine absorption was depressed (P<.05) only at pH 8.0. High dietary chloride (.89%) produced higher (P<.05) lysine absorption than a high dietary level of potassium (1.81%). No effect (P>.05) of dietary electrolytes on arginine absorption was detected. These results indicate that the dietary balance of monovalent electrolytes, and, hence, acid-base balance, may influence the intestinal absorption of lysine.