Stimulation of pancreatic growth by intraduodenal amino acids and HCl.

Exogenous secretin and cholecystokinin (CCK) have been shown to stimulate the growth of the exocrine pancreas. To conclude that a hormone produces an effect under normal physiological conditions, one must demonstrate that the endogenous hormone also produces the action in question. To release endogenous secretin 0.01 N HCl was continuously infused into the duodenums of eight rats for 5 days. Sixteen animals were prepared with catheters inserted 1 cm below the pylorus. The other eight animals were infused with PO4 buffer, pH 7.5. The infusion rate for both groups was 2 ml/h. Animals were killed at the end of 5 days, and the oxyntic gland mucosa and pancreas were examined. Pancreatic weights, DNA synthesis, DNa, RNA, and protein content were significantly increased in rats receiving acid. An identical experiment was set up to release endogenous CCK. In this experiment eight rats received a solution containing 50 mM phenylalanine and 50 mM tryptophan. The controls received the caloric equivalent in glucose. At the end of 1 wk the pancreases of the rats infused with amino acids averaged 405 (P < 0.001) heavier than the controls. Similar increases occurred in DNA, RNA, and protein content. These studies suggest that endogenous secretin and CCK can be released in amounts sufficient to stimulate growth.