Carbamylcholine stimulation of protein secretion in pancreatic acinar carcinoma of rat

Pancreatic acinar carcinoma fragments, pulse-chase labeled with [ ³ H]-leucine, responded to carbamylcholine chloride by increased secretion of [ ³ H]leucine-labeled protein into external buffer medium. Secretion of labeled protein by the carcinoma fragments increased in concentration-dependent fashion between 10 ^-8 -10 ^-5 M carbamylcholine, was completely inhibited at 4°C, and was accompanied by an equivalent increase in the secretion of preformed amylase. A maximally effective carbamylcholine concentration of 10 ^-5 M was observed for both carcinoma fragments and normal pancreas lobules. However, the maximal rate of protein secretion by the carcinoma fragments was only approximately one-fifth the rate determined for the normal pancreas lobules. This modest secretory response indicates a population of partially differentiated cells in the pancreatic acinar carcinoma which secrete less enzyme than fully differentiated adult pancreatic acinar cells. Secretory responsiveness can be utilized as a quantitative acinar cell response in studies on differentiation in pancreatic carcinoma.