Effects of Insulin-Like Growth Factor I (IGF-I) on the Porto-Arterial Concentration Differences of Amino Acids and Glucose:

Abstract

It is established that insulin-like growth factor I (IGF-I) influences cell differentiation and proliferation. Less is known, however, if such changes also influence the flow of nutrients from the intestinal lumen to the portal circulation. In the present study, we tested if IGF-I treatment (0.3 mg IGF-I/24 hr and kg) during 7 days affects the porto-arterial concentration differences of amino acids and glucose in piglets. Two routes of administration, oral and intraperitoneal, were compared. Following the IGF-I treatment, a bolus of nutrients was administered to the proximal duodenum and the porto-arterial concentration differences of amino acids and glucose were determined. We found that intraperitoneal administration of IGF-I significantly increased the difference in concentration between portal and arterial plasma for amino acids, whereas no such effect was seen with glucose. This might suggest that IGF-I has a specific effect on amino acid transporters in the intestinal wall. The same dose of IGF-I given orally did not exhibit the same effect on the absorption of amino acid as the animals which were given the peptide intraperitoneally.

Key words

IGF-I - Small Intestine - Piglet - Amino Acids - Glucose - Porto-Arterial Concentration Difference - Catheterisation