Further evidence that protein synthesis can be decreased in vivo following hormonal stimulation in the rat pancreas.

The present study has been undertaken to determine in the rat the influence of exocrine secretory stimulation on pancreatic protein synthesis. This stimulant consisted of a single injection of cholecystokinin-pancreozymin (8 Ivy units/kg) plus secretin (5 clinical units/kg). The rate of (14C) phenylalanine incorporation into total proteins was measured 5, 11, 17, 30, 45 and 60 min later. Incorporation was significantly decreased after 5 min, then significantly increased at 17 min, and finally returned to control values at 45 min. This biphasic evolution was shown not to be caused by variations in the precursor pool specific radioactivity. We concluded that secretory stimulation of the pancreas can induce a decrease in the rate of protein biosynthesis. This decrease is nevertheless a transient phenomenon, since the rate of biosynthesis was increased at 17 min. These results, obtained from a totally in vivo system, confirm previous data obtained from an in vivo-in vitro system.