Modulation of superoxide generation in in vivo lipopolysaccharide-primed rat alveolar macrophages by arachidonic acid and inhibitors of protein kinase C, phospholipase A2, protein serine-threonine phosphatase(s), protein tyrosine kinase(s) and phosphatase(s).
Ninety minutes after i.v. injection of Escherichia coli lipopolysaccharide (LPS) (1 mg/kg) into rats, phorbol 12-myristate 13-acetate (PMA)-stimulated superoxide anion (O2-) secretion was enhanced in suspensions of in vivo LPS-treated alveolar macrophages (AM phi) when compared with saline (SAL)-treated AM phi. The purpose of this investigation was to dissect the in vitro mechanism of PMA-stimulated O2- generation in both LPS and SAL-treated rat AM phi, with a panel of inhibitors of protein kinase C (PKC), protein serine-threonine phosphatase(s) (PSP), protein tyrosine kinase(s) (PTK) and phosphatase(s) (PTP), phospholipase A2 (PLA2), cyclooxygenase (CO) and 5-lipoxygenase (5-LO). The following agents blocked PMA-stimulated O2- generation in both LPS- and SAL-treated AM phi (expressed as percentage of control): 1) PKC inhibitors: staurosporine: 100 nM, 7.0% (LPS) and 5.6% (SAL); sphingosine: 10 microM, 21% (LPS) and 10.5% (SAL); 2) PTK inhibitor: genistein: 100 microM, 44% (LPS) and 31% (SAL); 3) PTP inhibitors: phenylarsine oxide, 10 microM, 12.1% (LPS) and 18% (SAL); diamide, 1000 microM, 10.1% (LPS) and 10.5% (SAL); and 4) PLA2 inhibitors: manoalide: 1 microM, 29.3% (LPS) and 5.2% (SAL); scalaradial: 1 microM, 7.7% (LPS) and 7.1% (SAL); and WAY 125,984: 10 microM, 17.1% (LPS) and 14.5% (SAL). In addition, it was observed that exogenously added arachidonic acid (AA)-stimulated O2- generation in a time- and dose-dependent manner in both LPS and SAL-treated AM phi. The following inhibitors enhanced or did not affect PMA-stimulated O2- generation in LPS- and SAL-treated AM phi (expressed as percentage of of control): 1) PSP inhibitors: okadaic acid: 0.5 microM, 117% (LPS) and 153% (SAL); calyculin A: 1 microM, 112% (LPS) and 101% (SAL); 2) CO and 5-LO inhibitors: indomethacin: 10 microM, 107% (LPS) and 90% (SAL); WY 50, 295: 1 microM, 99% (LPS) and 103% (SAL); and 3) the PTP inhibitor orthovanadate upon prolonged preincubation. In both in vivo LPS- or SAL-primed AM phi, PMA-stimulated O2- generation appears to be modulated by PKC, PLA2, AA, PTK, PTP and PSP. No modulatory role was evident for either CO or 5-LO metabolites. These findings might bear on the design of therapeutic approaches for the modulation of O2- release by AM phi in the early stages of sepsis and adult respiratory distress syndrome.
Mayer
A M
AM
Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, Illinois, USA.
Brenic
S
S
Stocker
R
R
Glaser
K B
KB
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000502:physiology; D054467:Phospholipases A2; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D013481:Superoxides; D016718:Arachidonic Acid; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases; D013755:Tetradecanoylphorbol Acetate