Intestinal transport of dipeptides in man: relative importance of hydrolysis and intact absorption

摘要: A 30 cm segment of the duodenum, jejunum, or ileum normal human volunteers was perfused, on separate occasions, with test solutions containing either glycylglycine, free glycine, glycylleucine, equimolar amounts glycine and leucine. Luminal fluid contained no hydrolytic activity against glycylglycine minimal glycylleucine. In each intestinal segment, amino acid absorption rates were significantly greater from same amount acids in dipeptide than form(as high as 185% increase). Perfusion a solution mixture leucine always resulted rate. This preferential leucine, however, diminished (jejunum) almost abolished (duodenum ileum) when glycylleucine instead presented to mucosa. Among three segments, duodenum exhibited least potential for disappearance dipeptides. The jejunal ileal similar (94% vs. 92%) slightly different (92% 79%). Despite lack remarkable difference rates, constituent markedly jejunum ileum. reduced brought about by accumulation lumen (3 10-fold difference). Inhibition during perfusion intestine did not result any concentration contain Similarly, inhibition isoleucine accompanied alteration results these studies suggest that: (a) gut is principally accomplished intact hydrolysis; (b) intracellular hydrolysis dipeptides while are only two segments; (c) there appreciable membrane-bound enzymes small fraction hydrolyzed enzymes.