Agents that enhance intestinal glutamine transport may be useful under conditions in which intestinal mucosal function is compromised. Here we examined whether oral administration of insulin-like growth factor (IGF-I) stimulates absorption of L-glutamine in piglet intestine. Colostrum-deprived piglets received human recombinant IGF-I (3.5 mg/kg/day) or vehicle orogastrically every 8 hr for four days after birth. Piglets were killed on day 5 and the proximal jejunum was removed. Basal electrical parameters and L-glutamine-stimulated changes in short-circuit current were measured in muscle-stripped tissues, and rates of L-glutamine uptake were measured in everted jejunal sleeves. Oral IGF-I had no effect on jejunal mucosal mass. Short-circuit current responses to mucosal addition of 10 mM L-glutamine were increased by oral IGF-I. Total and carrier-mediated uptakes of L-glutamine per milligram were greater in tissues from IGF-I-treated piglets due to a significantly greater maximal rate of uptake (Jmax). Thus, oral administration of IGF-I stimulates Na+-dependent glutamine absorption in piglet small intestine, an effect that is independent of changes in intestinal mucosal mass.
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