Enhancement of Ca2+-regulated exocytosis by indomethacin in guinea-pig antral mucous cells: arachidonic acid accumulation.
Ca2+-regulated exocytosis is enhanced by an autocrine mechanism via the PGE2-cAMP pathway in antral mucous cells of guinea-pigs. The inhibition of the PGE2-cAMP pathway by H-89 (an inhibitor of protein kinase A, PKA) or aspirin (ASA, an inhibitor of cyclo-oxygenase, COX) decreased the frequency of ACh-stimulated exocytotic events by 60%. Indomethacin (IDM, an inhibitor of COX), however, decreased the frequency of ACh-stimulated exocytotic events only by 30%. Moreover, IDM increased the frequency of ACh-stimulated exocytotic events by 50% in H-89-treated or ASA-treated cells. IDM inhibits the synthesis of Prostaglandin (PGG/H) and (15R)-15-hydroxy-5,8,11 cis-13-trans-eicosatetraenoic acid (15R-HPETE), while ASA inhibits only the synthesis of PGG/H. Thus, IDM may accumulate arachidonic acid (AA). AACOCF3 or N-(p-amylcinnamoyl) anthranilic acid (ACA; both inhibitors of phospholipase A2, PLA2), which inhibits AA synthesis, decreased the frequency of ACh-stimulated exocytotic events by 60%. IDM, however, did not increase the frequency in AACOCF3-treated cells. AA increased the frequency of ACh-stimulated exocytotic events in AACOCF3- or ASA-treated cells, similar to IDM in ASA- and H-89-treated cells. Moreover, in the presence of AA, IDM did not increase the frequency of ACh-stimulated exocytotic events in ASA-treated cells. The PGE2 release from antral mucosa indicates that inhibition of PLA2 by ACA inhibits the AA accumulation in unstimulated and ACh-stimulated antral mucosa. The dose-response study of AA and IDM demonstrated that the concentration of intracellular AA accumulated by IDM is less than 100 nm. In conclusion, IDM modulates the ACh-stimulated exocytosis via AA accumulation in antral mucous cells.
Fujiwara
Shoko
S
Department of Physiology, Osaka Medical College, 2-7 Daigakucho, Takatsuki 569-8686, Japan.
Shimamoto
Chikao
C
Nakanishi
Yoshihiko
Y
Katsu
Ken-ichi
K
Kato
Masumi
M
Nakahari
Takashi
T
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001095:Arachidonic Acids / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D002934:Cinnamates / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005089:Exocytosis / Q000187:drug effects*; D005753:Gastric Mucosa / Q000187:drug effects* / Q000378:metabolism; D006168:Guinea Pigs; D007213:Indomethacin / Q000494:pharmacology*; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D011706:Pyloric Antrum / Q000187:drug effects* / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D062367:ortho-Aminobenzoates / Q000494:pharmacology
D001095:Arachidonic Acids; D002934:Cinnamates; D016861:Cyclooxygenase Inhibitors; D007546:Isoquinolines; D013449:Sulfonamides; D062367:ortho-Aminobenzoates; C081565:arachidonyltrifluoromethane; C085901:4-amylcinnamoylanthranilic acid; D016718:Arachidonic Acid; D017868:Cyclic AMP-Dependent Protein Kinases; D010741:Phospholipases A; D054467:Phospholipases A2; D015232:Dinoprostone; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D000109:Acetylcholine; D001241:Aspirin; D007213:Indomethacin