Amino Acid Uptake and Amylase Secretion in Isolated Rat Pancreatic Lobules In Vitro: Interactions Between Carbachol, Insulin, Phorbor Ester and Ethanol

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In the present study we examined the effects of bovine insulin, 12-O-teradecanoylphorbol-13-acetate (TPA), carbachol and ethanol on amino acid uptake and amylase secretion from isolated rat pancreatic lobules in vitro. Net L- [3H] serine uptake, assessed relative to D- [14C] mannitol, was saturable, enhanced by insulin (1 mU/ml) and TPA (10-6 M) but inhibited by carbachol (10-5 M) and ouabain (0.1 mM) . Ethanol (65 mM) had no significant effect on L-serine accumulation or amylase release from lobules incubated in the absence or presence of carbachol (10-5M) . Amylase secretion was markedly stimulated by carbachol, whereas atropine (10-5 M) simultaneously blocked enzyme secretion and reversed the inhibition of net L-serine uptake induced by carbachol. Basal amylase release was unaffected by insulin but stimulated by TPA. Submaximal concentrations of carbachol (10-7 M) and TPA (2×10-8 M) only caused an additive response in amylase secretion. The carbachol-induced depression in net amino acid uptake may reflect enhanced tracer efflux and altered ionic gradients. The similar stimulatory effects provoked by insulin and TPA suggest a possible regulatory role for protein kinase C in enhancing amino acid accumulation in the exocrine pancreas.
昭和大学・昭和医学会の論文