Effect of somatostatin on plasma amino acid uptake by human pancreas.

We studied the effect of somatostatin on amino acid uptake by pancreatic acinar cells in 12 healthy male volunteers, aged 20-48 yr. Pancreatic amino acid uptake was assessed by measuring free plasma amino acid concentration before and during pancreatic stimulation with secretin (1 CU/kg body wt.h) and cerulein (50 ng/kg body wt.h). Pancreatic stimulation with these peptides caused a significant decrease in plasma amino acid concentrations. Somatostatin, given at the dosages of 0.15 and 1.35 micrograms/kg body wt.h, significantly diminished this decrease. The effect of the higher dose of somatostatin was more marked than that produced by the lower dose, compatible with dose dependence. The results suggest that somatostatin is able to inhibit the amino acid uptake by the pancreatic acinar cells. This inhibitory effect could be an important mechanism by which the peptide decreases pancreatic enzyme secretion.