Intravenous amino acids and fat stimulate pancreatic secretion.

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Abstract
The pancreatic secretory effects of natural amino acids (AA), given either as a mixture simulating the composition of serum albumin or individually, and fat emulsion administered i.v. or intraduodenally with or without secretin in 4 chronic pancreatic fistula dogs were compared. Both the AA mixture and fat emulsion given i.v. in graded doses (10-160 ml/h) resulted in a dose-dependent rise in pancreatic protein secretion, reaching a peak of about 40% of the maximal response to the octapeptide of cholecystokinin (OP-CCK). The comparison of the secretogogue activity of individual AA shows that L-tryptophan and L-phenylalanine exhibited the strongest stimulation of protein secretion, reaching 64% and 67%, respectively, of OP-CCK maximum. With the i.v. infusion of 50 mM solution of L-tryptophan and L-phenylalanine mixture given in graded doses (range 2-32 mmol/h), the highest observed protein response was not significantly different from that obtained by intraduodenal instillation of these AA and amounted to about 67% of the OP-CCK maximum. The major difference between these 2 routes of administration was that AA and fat administered i.v. did not affect secretin-induced pancreatic secretion, whereas those given intraduodenally caused a marked augmentation of this response. Both AA and fat infused i.v. result in substantial stimulation of pancreatic protein secretion, suggesting that these nutrients absorbed from the gut may account at least in part for the intestinal phase stimulation of pancreatic secretion.