Rat pancreas adenylate cyclase

1. 1. The responsiveness of adenylate cyclase and enzyme secretion for secretin and the C-terminal octapeptide of pancreozymin has been investigated in particulate fractions of the pancreas of five different species. 2. 2. The adenylate cyclase is sensitive to the C-terminal octapeptide of pancreozymin in all species investigated. 3. 3. The enzyme is much more sensitive to secretin in rat and cat than in mouse and rabbit, whereas with guinea pig intermediate values are obtained. 4. 4. The enzyme secretion is stimulated by secretin in pancreatic fragments of rat and cat, but not in those of mouse and rabbit. 5. 5. These results suggest that in species where secretin stimulated enzyme secretion, it does so by stimulating the adenylate cyclase system.