Abstract
Cholecystokinin, gastrin and pentapeptide stimulated cyclic 3', 5'-adenosine monophosphate-phosphodiesterase (PDE) from a number of rabbit tissues including the gall bladder. The stimulation is effected by a shift in activity from a high Km form of PDE (PDE-I) to a low Km form (PDE-II) of the enzyme. At low concentrations the peptides stimulated the enzyme and when added in high concentrations they inhibited the enzyme activity. Tetrapeptide consistently inhibited PDE activity. The hypothesis is presented that gastrin and cholecystokinin may act via stimulation of PDE and a resultant decrease in intracellular cyclic 3', 5'-adenosine monophosphate levels. This hypothesis is in harmony with most of the known physiology and pharmacology of these hormones. Further-more, it provides an explanation for the antagonism between each of these hormones and secretin on gastric acid secretion.
Footnotes
- Received July 23, 1971.
- Accepted August 22, 1972.
- © 1972 by The Williams & Wilkins Co.
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