Effect of Tetracaine on Pancreatic Protein Synthesis 1

Abstract

The major interest regarding the pancreatic acinar cell function concerns the mechanism whereby processes of secretion and synthesis are integrated. We now have good evidence from in vivo experiments that feeding (1), cholinergic drugs and pan-creozymin (2) are associated with increased pancreatic enzyme secretion as well as synthesis. Moreover, recent data obtained in vivo (3) and in vitro (4) suggest that changes in the rate of protein synthesis are related to the secretion of the digestive enzymes.

Experiments performed with atropine failed to demonstrate such a dissociation between the two processes; indeed, the anti-cholinergic drug was shown to initially reduce enzyme secretion in pigeons (5) and cats (6) and later, to decrease protein (5) and RNA synthesis in pigeons (7). In search for an inhibitor of the pancreozymin effect on pancreatic enzyme secretion, it was recently shown that tetracaine blocked secretion initiated by both the duodenal hormone and urecholine (8). The present investigation was therefore performed to determine if the local anesthetic also cause a reduction in protein synthesis and thus perhaps add another evidence for the control of pancreatic protein synthesis by some factors related to the secretory process.

Materials and Methods. Studies were performed using male albino rats of Sprague-Dawley strain (335-355 g wt). Before sacrifice, they were prepared under a definite schedule as previously described (4).

In vivo experiments. Control rats received intraperitoneally 0.5 cc of saline; treated rats received 14.7 mg/kg of tetracaine. All animals were sacrificed by decapitation 30 min after the injection and their pancreases were incubated as described in the in vitro experiments.

In vitro experiments and L-phenylalanine-¹⁴C incorporation studies. Rats were sacrificed and their pancreas removed; fat and excess tissue were trimmed and pieces of pancreatic tissue (400 mg) were incubated in tissue culture media (5 ml) containing 1 /xCi of L-phenylalanine-¹⁴C (0.37 mCi/μmole) for 30 min at 37°.