Modulation of superoxide anion generation by manoalide, arachidonic acid and staurosporine in liver infiltrated neutrophils in a rat model of endotoxemia.
Early accumulation of polymorphonuclear leukocytes (PMN) in the liver after in vivo exposure to Escherichia coli lipopolysaccharide (LPS) and concomitant in vitro phorbol myristate acetate (PMA)-stimulated superoxide anion (O2-) generation has recently been described in a rat model of endotoxemia. The purpose of this investigation was to study the role of phospholipase A2 (PLA2), arachidonic acid (AA), its metabolites, and protein kinase C (PKC) in the mechanism of PMA-stimulated O2- generation of liver infiltrated PMN as compared to circulating blood PMN. Rat PMN were isolated after a 1.5-h infusion of saline or LPS from the blood (SAL-PMN) or the liver (LPS-PMN), respectively. The following results were observed in both SAL-PMN and LPS-PMN: 1) Inhibitors of cyclooxygenase (indomethacin) and 5-lipoxygenase [eicosatetraynoic acid, WY 50,295 tromethamine and VZ 65, 4-(11-hydroxy-1,9-undecadiin)-brenzcatechin] pathways did not inhibit O2- generation; 2) the potent marine PLA2 inhibitor Manoalide inhibited O2- generation in a dose-dependent manner (IC50 = 0.5 microM); 3) exogenously added AA enhanced PMA-stimulated O2- generation in a time- and dose-dependent manner and partially reversed the effect of Manoalide in LPS-PMN; 4) staurosporine, a putative PKC inhibitor, blocked PMA-stimulated O2- generation completely in the absence of AA and 79% in the presence of AA. It was concluded that LPS-induced liver sequestration of PMN does not alter the role PLA2, AA and PKC play in PMA-stimulated O2- generation. These findings should have implications on the design of novel therapeutic approaches for the modulation of O2- release in the pathogenesis of LPS hepatotoxicity.
Mayer
A M
AM
Department of Physiology, Louisiana State University Medical Center, New Orleans.
Spitzer
J A
JA
D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology* / Q000502:physiology; D002248:Carbon Monoxide / Q000494:pharmacology; D004731:Endotoxins / Q000633:toxicity*; D005230:Fatty Acids, Nonesterified / Q000502:physiology; D007728:Kupffer Cells / Q000502:physiology; D016859:Lipoxygenase Inhibitors; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D009504:Neutrophils / Q000378:metabolism*; D010741:Phospholipases A / Q000502:physiology; D054467:Phospholipases A2; D011493:Protein Kinase C / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019311:Staurosporine; D013481:Superoxides / Q000378:metabolism*; D013729:Terpenes / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D004731:Endotoxins; D005230:Fatty Acids, Nonesterified; D016859:Lipoxygenase Inhibitors; D013729:Terpenes; D013481:Superoxides; D016718:Arachidonic Acid; D002248:Carbon Monoxide; C045673:manoalide; D011493:Protein Kinase C; D010741:Phospholipases A; D054467:Phospholipases A2; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate