Nicotine stimulation of protein secretion from isolated rat pancreatic acini

Abstract

The secretion of amylase and trypsinogen from isolated rat pancreatic acini was greatly stimulated by 3-25 mM nicotine. In the presence of 12.5 mM nicotine, a concentration used in the study, amylase and trypsinogen release was increased by 95 and 400%, respectively, when compared with the corresponding control and showed further a preferential release of trypsinogen. A 90-min time course release of the enzymes revealed that in the presence of nicotine trypsinogen-to-amylase ratio remained two- to threefold elevated over that of the control throughout the incubation period. The nicotine-induced stimulation of trypsinogen and amylase release from the acini could not be blocked by 2.5 mM cycloheximide, a dose that inhibited overall acinar protein synthesis by about 85%. When isolated acini were incubated with [3H]leucine in the presence of nicotine, the released proteins revealed a fourfold higher radioactivity (dpm/microgram acinar DNA) than the control. Cycloheximide dramatically decreased this increment. The rate of release of 3H-pulse-labeled proteins from the acini was greatly accelerated by nicotine. It is concluded that nicotine stimulates the secretion of preformed zymogen granules and newly synthesized proteins from dispersed rat pancreatic acini in vitro.