Pancreatic polypeptide responses to a meal and to intraduodenal amino acids and sodium oleate.

Serum concentrations of immunoreactive pancreatic polypeptide (IR-PP) were measured in dogs in response to a meal and to intraduodenal infusions of amino acids, Na oleate, and HCl. In addition, the effects of somatostatin on meal-stimulated IR-PP concentrations were studied. In response to a meal, IR-PP rose from 151 +/- 19 pg/ml to 296 +/- 35 pg/ml (P less than 0.01) at 15 min, reached a plateau of 367 +/- 56 pg/ml at 45 min, and remained elevated for 4 h. In response to intraduodenal amino acids, IR-PP rose from 196 +/- 22 pg/ml to 342 +/- 19 pg/ml (P less than 0.01), and serum alanine rose from 251 +/- 18 mM to 361 +/- 30 mM. Peak concentrations of IR-PP, however, were reached before alanine rose above baseline. During administration of intraduodenal Na oleate, IR-PP rose from 181 +/- 21 pg/ml to 348 +/- 17 pg/ml (P less than 0.01). Intraduodenal HCl had no effect on IR-PP. Intravenous somatostatin (100 microgram/h) suppressed meal-stimulated IR-PP from 450 +/- 68 pg/ml to 133 +/- 23 pg/ml (P less than 0.01). The data indicate 1) IR-PP is increased after a meal and intraduodenal administration of amino acids and Na oleate; 2) the increases in serum IR-PP precede increases in serum levels of absorbed alanine; and 3) somatostatin suppresses the meal-stimulated increase in serum IR-PP.