PP infusion in man: Pharmacokinetics at three dose levels and effects on gastrointestinal and pancreatic hormones

In order to elucidate the pharmacokinetics of PP in man and to investigate possible effects on gastrointestinal and pancreatic hormones, bovine PP was infused into 23 healthy volunteers after an overnight fast. During the low dose PP infusion ( 1 pmol/kg/min) a highly significant reduction in fasting plasma motilin levels was observed with a mean fall of 77% SEM 3% (p < 0.001). By contrast at doses up to 5 pmol/kg/min PP had no effect on circulating levels of gastrin, secretin, glucagon, insulin or blood glucose in the fasting state. BPP is rapidly cleared from the bloodstream in man at plasma concentrations comparable to and above those observed postprandially. The sustained elevation of this hormone after a meal cannot therefore be accounted for by a low metabolic clearance rate. The marked reduction in circulating motilin levels may explain some of the actions by PP on gastrointestinal motor activity.