Physiological control of gastric acid secretion

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Studies on the inactivation of pancreozymin concentrates

The loss in hormonal activity resulting on incubation of pancreozymin concentrates with canine blood serum at 37°C has been investigated. The test extracts comprised (SI), a solid obtained from treatment of a salted acid extract of the upper intestinal mucosa with trichloroacetic acid and the amine precipitate, (AP), derived from SI. The decrease in activity was determined in relation to an incubated concentrate-saline solution in dogs with the main pancreatic duct cannulated. Fluid secretion was promoted by potent secretin preparations in saline administered by single injection or by continuous infusion. As based on the total amylase content of the pancreatic juice samples, the hormonal concentrates underwent rather small losses in activity, the AP requiring higher dilutions with serum for an effect as compared to SI. Canine liver extract and a hog kidney diamine oxidase concentrate caused inactivation of pancreozymin products but bovine and canine plasma protein fractions, heavy metal salt and thiol solutions and possibly, human urine, were without action.

A further physiological role for naturally occurring trypsin inhibitors: the evidence for a trophic stimulant of the pancreatic acinar cell

The oral ingestion of naturally occurring purified trypsin inhibitors from soybean, ovomucoid, and bovine pancreas has been demonstrated to be a potent stimulus to pancreatic digestive enzyme synthesis. This effect may be so marked as to lead to impairment of growth in the rat and chicken through the faecal loss of essential amino acids. This is thought to be due to the markedly potentiated secretion of pancreatic digestive enzyme protein overwhelming the normal digestive capacity of the gastrointestinal tract and resulting in a pancreatogenous protein-losing enteropathy. Experimental evidence is presented to suggest that this response to the trypsin inhibitors requires the mediation of the gastrointestinal tract and is independent of vagal innervation to the pancreas. The most satisfactory hypothesis would favour the release of a trophic stimulus from the intestinal mucosa (possibly pancreozymin-cholecystokinin) to the acinar cell of the pancreas in response to the presence of the trypsin inhibitor in the bowel lumen. It is suggested that a primary function of the endogenously secreted pancreatic trypsin inhibitor may be to potentiate enzyme synthesis by the acinar cell, providing an important stimulus for the repletion of the digestive enzymes. Some of the potential physiological and clinical implications of such a mechanism are discussed.