Intestinal adaptation in diabetes: amino acid absorption.

LAL, DHEERAJ, AND HAROLD P. SCHEDL. Intestinal adaptation in diabetes: amino acid absorption. Am. J. Physiol. 227(4): 827-831. 1974.-Since the diabetic rat shows adaptations in intestinal hexose absorption, we studied amino acid absorption 5 and 12 days after induction of diabetes with alloxan or streptozotocin. We perfused the entire small intestine intraluminally with 5 mM amino acid solutions and measured absorption as loss from the lumen. At 5 days after injection, dry weights of intestine and mucosa were similar in control and diabetic groups. Total absorption was increased for L-leucine and L-lysine, but not for glycine, L-proline, or cr-aminoisobutyric acid (AIB). Since intestinal and mucosal weights were practically the same in controls and diabetics, increased leucine and lysine absorptions in diabetics were the result of stimulation of transport per unit of mucosa. At 12 days, dry weight of mucosa was 40-60% greater in diabetics than controls. Total absorption of leucine, lysine, and AIB increased in diabetics in proportion to mucosal mass. Hence absorption per unit of mucosa was the same in controls and diabetics for all three amino acids at 12 days. Leucine is absorbed by the neutral, lysine by the basic, and the other amino acids by the imino acidglycine pathway. Therefore, stimulation of absorption per unit of mucosa at 5 days is selective and is superceded at 12 days by enhancement of absorption through increased mucosal growth in diabetics, a general process for all amino acids studied.