title: Cyclic GMP inhibits protein kinase C-mediated secretion in rat pancreatic acini.
abstract: Dibutyryl cyclic GMP (Bu2cGMP) inhibited agonist-induced secretion of amylase from isolated rat pancreatic acini. In contrast to previous studies, this inhibitory action was not confined to butyryl derivatives of cyclic GMP, since the membrane-permeant cyclic GMP analogues Bu2cGMP and cyclic 8-bromo-GMP (8-Br-cGMP) were equipotent (IC50 2 nM) in their inhibition of amylase secretion stimulated by cholecystokinin-(26-33)-octapeptide (CCK8): at extracellular concentrations up to 1 mM, cyclic GMP itself was devoid of inhibitory activity. Both Bu2cGMP and 8-Br-cGMP also potently inhibited secretion stimulated by 4 beta-phorbol 12-myristate 13-acetate (PMA) (IC50 6 nM), but only partially inhibited responses elicited by bethanechol or bombesin and were without effect on A23187-evoked secretion. Furthermore, agents that are known to raise intracellular cyclic GMP levels (MB22948 (2-o-propoxyphenyl-8-azapurin-6-one) or nitroprusside) or antagonize the actions of protein kinase C (4 alpha-PMA or staurosporine), also inhibited CCK8- or PMA-stimulated secretion but not secretion elicited by bombesin, bethanechol, or A23187. It is concluded from these and other observations reported here that protein kinase C is the major intracellular mediator of amylase secretion stimulated by CCK8 and that this pathway may be regulated by cyclic GMP at a step that follows protein kinase C activation.
mesh_terms: D000681:Amylases / Q000378:metabolism*; D000818:Animals; D018723:Bethanechol; D001626:Bethanechol Compounds / Q000494:pharmacology; D001839:Bombesin / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology*; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology*; D010189:Pancreatic Juice / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D012844:Sincalide / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D001626:Bethanechol Compounds; D018723:Bethanechol; C016276:8-bromocyclic GMP; D003995:Dibutyryl Cyclic GMP; D000001:Calcimycin; D011493:Protein Kinase C; D000681:Amylases; D006152:Cyclic GMP; D012844:Sincalide; D013755:Tetradecanoylphorbol Acetate; D001839:Bombesin; D002118:Calcium