4-amylcinnamoylanthranilic-acid and arachidonyltrifluoromethane

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.

Topics: Acetylcholine; Animals; Arachidonic Acid; Arachidonic Acids; Aspirin; Calcium Signaling; Cells, Cultured; Cinnamates; Cyclic AMP-Dependent Protein Kinases; Cyclooxygenase Inhibitors; Dinoprostone; Dose-Response Relationship, Drug; Exocytosis; Gastric Mucosa; Guinea Pigs; Indomethacin; Isoquinolines; Male; ortho-Aminobenzoates; Phospholipases A; Phospholipases A2; Pyloric Antrum; Sulfonamides; Time Factors

Arachidonyltrifluoromethy ketone (AACOCF(3)), a phospholipase A(2) antagonist, reversibly induced dispersal of Golgi stack- and trans Golgi network (TGN)-resident proteins throughout the cytoplasm in NRK cells as followed by immunocytochemical staining of ManII and TGN38, respectively. The action of AACOCF(3) was partly blocked by other PLA(2) antagonists, suggesting it be not caused by a general inhibition of phospholipase A(2). AACOCF(3) neither dissociated beta-COP from membranes nor prevented brefeldin A-induced beta-COP release. Action of AACOCF(3) on the Golgi stack and TGN is different from that of brefeldin A and nordihydroguaiaretic acid. The most prominent difference is that the Golgi stack and TGN showed a similar sensitivity to AACOCF(3), while the TGN was dispersed more slowly than the Golgi stack in brefeldin A- or nordihydroguaiaretic acid-treated NRK cells. This novel action of AACOCF(3) may be used as pharmacological tool and give new insights into vesicle-mediated traffic and Golgi membrane dynamics.

Topics: Aminobenzoates; Animals; Arachidonic Acids; Biological Transport; Brefeldin A; Cell Line; Chlorobenzoates; Cinnamates; Coatomer Protein; Cytoplasm; Dose-Response Relationship, Drug; Endoplasmic Reticulum; Enzyme Inhibitors; Golgi Apparatus; Masoprocol; Membrane Proteins; Microscopy, Fluorescence; Naphthalenes; ortho-Aminobenzoates; Phospholipases A; Pyrones; Time Factors