The role of extracellular Ca2+ and cyclic nucleotides in the mechanism of enzyme secretion from the cat pancreas.
The role of Ca2+ in protein secretion from the isolated perfused cat's pancreas, the effect of the dibutyryl analogues of cAMP and cGMP, and the interrelation of Ca2+ and the nucleotides were studied. The following results were obtained: 1. Pancreatic enzyme secretion can be elicited by CaCl2 injections into the pancreatic arteries and is linearily related to the peak Ca2+ concentration in the effluent perfusate. Different background Ca2+ concentrations in the perfusate (3 mM or 0.125 mM) do not disturb this relation, indicating that no adaptation occurs. The effect of Ca2+ injections is of the same magnitude as that evoked by the hormones pancreozymin or acetylcholine. 2. Injections of Ca2+ potentiate the effects of dibutyryl adenosine 3',5'-cyclic monophosphate (dbcAMP), dibutyryl guanosine 3',5'-cyclic monophosphate (dbcGMP) or theophylline. 3. Infusion of low doses of pancreozymin increases the Ca2+ effect. The findings indicate that extracellular Ca2+ is involved in the mechanism of enzyme secretion and that Ca2+ and cyclic nucleotides have a synergistic action on the target.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002415:Cats; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D004357:Drug Synergism; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D008297:Male; D009712:Nucleotides, Cyclic / Q000494:pharmacology*; D010179:Pancreas / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D013806:Theophylline / Q000494:pharmacology
D009712:Nucleotides, Cyclic; D011506:Proteins; D013806:Theophylline; D000242:Cyclic AMP; D006152:Cyclic GMP; D002118:Calcium