Changes in plasma CCK concentrations in luminal feedback regulation in the conscious rat

The effects of bile-pancreatic juice diversion on pancreatic secretion and changes in plasma CCK-8 equivalents were determined in conscious rats. Rats were prepared with cannulae, draining pure pancreatic juice and bile separately. Plasma CCK-8 equivalents were bioassayed, based on their ability to stimulate amylase release from isolated rat pancreatic acini. Diversion of bile-pancreatic juice resulted in an extreme increase in pancreatic protein output. Plasma CCK bioactivity also increased by BPJ diversion, peaked at 2 hours after the begining of BPJ diversion, then slightly declined and continued for 24 hours. The changes in plasma CCK concentraions almost paralleled with the change in protein output. These results indicate that the feedback regulation of pancreatic secretion in the consious rat is mediated by the release of chlecystokinin.