Action of cholecystokinin and caerulein on the rabbit sphincter of Oddi.

The action of cholecystokinin (CCK) and caerulein upon the rabbit sphincter of Oddi was investigated by electromyography, manometry and measuring of the flow. Intravenous injection of CCK resulted in a marked rise of the sphincter activity with a maximum at the 1st min and return to the basal level at the 10th min. Injection of increasing doses of hormone showed that the effect was proportional to the logarithm of the dose. The same results were obtained with caerulein. Parallely, CCK provoked a rise of the biliary pressure also proportional to the logarithm of the dose and a reduction to the biliary flow. The discrepancies between these results and some other experiments are discussed. It is concluded that, in the rabbit, CCK increases the activity of the sphincter of Oddi.