Hormonal Stimulation of α-Amylase Synthesis in Porcine Pancreatic Minces

Abstract

Minces of porcine pancreas maintained a linear rate or protein synthesis for more than 4 h with similar kinetics in the presence of absence of hormones. alpha-Amylase protein, quantitated by using glycogen percipitation, SDS polyacrylamide gel analysis, and radioimmunoassay, was found to represent 6-7% of the total protein content of the minces. The addition of prostaglandin E1 (10-7M), or a pancreozymin preparation (3-10 Crick-Harper-Raper units/ml) to the incubation media produced within 60 min an increase in alpha-amylase protein above that stored in the tissue 10- to 20-fold greater than that observed in control minces. The addiction of cAMP analogs (10(-3)M) to the medium produced a more variable stimulation of alpha-amylase content. Quantitation of the incorporation of radiolabeled amino acid into alpha-amylase protein with simultaneous determination of the specific activity of the precursor pool suggested that these agents produced at least 3- to 5-fold stimulation of de novo alpha-amylase synthesis. This stimulation was not the result of decreased rates of alpha-amylase catabolism. The addition of actinomycin D (20 mug/ml), a concentration inhibiting more than 93% of new RNA synthesis, failed to alter the stimulation of alpha-amylase synthesis by these agents. Apparent hormonal stimulation of non-alpha-amylase protein synthesis was also observed.