title: Involvement of cyclic AMP generation in the inhibition of respiratory burst by 2-phenyl-4-quinolone (YT-1) in rat neutrophils.
abstract: The inhibitory effect of 2-phenyl-4-quinolone (YT-1) on respiratory burst in rat neutrophils was investigated, and the underlying mechanism of action was assessed. YT-1 caused a concentration-dependent inhibition of the rate of O2.- release from rat neutrophils in response to formylmethionyl-leucyl-phenylalanine (fMLP), but not to phorbol 12-myristate 13-acetate (PMA), with an IC50 value of 60.7+/-8.2 microM. A comparable effect was also demonstrated in the inhibition of O2 consumption. Unlike superoxide dismutase, YT-1 had no effect on O2.- generation in the xanthine-xanthine oxidase system and during dihydroxyfumaric acid autoxidation. The fMLP-induced inositol trisphosphate (IP3) formation was unaffected by YT-1. In addition, YT-1 did not affect the initial spike of [Ca2+]i, but it accelerated the rate of [Ca2+]i decline in cells in response to fMLP. YT-1 was found to have little effect on the activity of neutrophil cytosolic protein kinase C (PKC). YT-1 increased the cellular cyclic AMP level, while having no effect on the cyclic GMP level. In addition, YT-1 increased neutrophil cytosolic protein kinase A (PKA) activity, but had no direct effect on the enzyme activity of pure porcine heart PKA. When neutrophils were treated with (8R,9S,11S)-(-)-9-hydroxy-9-hexoxycarbonyl-8-methyl-2,3,9,10-tetra hydro-8,11-epoxy- 1H,8H,11H-2,7b,11a-triazadibenzo[a,g]cycloocta[cde]trinde n-1-one, (KT 5720), a PKA inhibitor, the inhibition of O2.- generation by YT-1, as well as by prostaglandin E1 (PGE1) and dibutyryl cyclic AMP, was attenuated effectively. YT-1 did not activate the adenylate cyclase associated with neutrophil particulate fraction but inhibited the cytosolic phosphodiesterase (PDE) activity in a concentration-dependent manner. Neutrophils treated with YT-1 had a more pronounced increase in cellular cyclic AMP level by PGE1. Moreover, the ability of PGE1 to inhibit the respiratory burst in neutrophils was greatly enhanced by YT-1. These results suggest that the increase in cellular cyclic AMP levels by YT-1 through the inhibition of PDE (probably PDE4 isoenzyme) activity is involved in its inhibition of fMLP-induced respiratory burst in rat neutrophils.
authors.affiliation: Department of Medical Research, Taichung Veterans General Hospital, Taiwan, Republic of China.
authors.forename: J P
authors.initials: JP
authors.lastname: Wang
authors.forename: S L
authors.initials: SL
authors.lastname: Raung
authors.forename: L J
authors.initials: LJ
authors.lastname: Huang
authors.forename: S C
authors.initials: SC
authors.lastname: Kuo
mesh_terms: D000262:Adenylyl Cyclases / Q000097:blood; D000527:Alprostadil / Q000494:pharmacology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000097:blood; D002227:Carbazoles; D002316:Cardiotonic Agents / Q000494:pharmacology; D000242:Cyclic AMP / Q000097:blood*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000097:blood; D006152:Cyclic GMP / Q000097:blood; D003600:Cytosol / Q000201:enzymology; D007211:Indoles / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000097:blood; D007295:Inositol Phosphates / Q000097:blood; D007700:Kinetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects / Q000502:physiology*; D010101:Oxygen Consumption / Q000187:drug effects; D011493:Protein Kinase C / Q000097:blood; D011758:Pyrroles / Q000494:pharmacology; D015363:Quinolones / Q000494:pharmacology*; D051381:Rats; D016897:Respiratory Burst / Q000187:drug effects* / Q000502:physiology; D013481:Superoxides / Q000097:blood; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D002227:Carbazoles; D002316:Cardiotonic Agents; D007211:Indoles; D007295:Inositol Phosphates; D011758:Pyrroles; D015363:Quinolones; D013481:Superoxides; C084179:2-phenyl-4-oxohydroquinoline; C057416:KT 5720; D009240:N-Formylmethionine Leucyl-Phenylalanine; D003994:Bucladesine; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D000527:Alprostadil; D006152:Cyclic GMP; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium