Comparative bio-assay of secretin and pancreozymin in rats and dogs

Abstract

The dose-response relationship of secretin and volume flow and of pancreozymin and enzyme production was explored in the rat and dog. The relative sensitivity of the two species to the same secretin and pancreozymin preparations was compared. Anesthetics such as ether, chloroform, secobarbital, or pentobarbital sodium depressed the response of the rat to secretin. Linearity of response to secretin was observed in both rats and dogs; the range in the dog was 0.03– 0.5 mg/kg, whereas in the rat it was approximately 1.25–12.5 mg/kg. The threshold dose of secretin was the same for anesthetized and conscious rats, but the response of conscious rats to identical doses was much greater than that of anesthetized rats. A linear relationship between enzyme output and log dose of pancreozymin was found in both species; the dose range in the dog was from 2.5 to 1,000 µg, whereas in the rat the threshold dose was about 1 mg. Thus, the dog is more sensitive to both secretin and pancreozymin than the rat. Since results in the dog were easily reproducible, the dog is still the animal of choice for bio-assay of secretin and pancreozymin.