Influence of cyclooxygenase and lipoxygenase inhibitors on oxidative stress-induced lung injury.
OBJECTIVE
Hypochlorous acid (HOCl) is the main oxidant of activated neutrophil granulocytes. It is generated by their myeloperoxidase during respiratory burst. This study investigates the effects of HOCl on vascular permeability and pulmonary artery pressure (PAP) and characterizes the influence of the cyclooxygenase inhibitor acetylsalicylic acid (ASA) and the 5-lipoxygenase inhibitor caffeic acid (CaA) on the observed alterations.


METHODS
Prospective experimental study using isolated perfused rabbit lungs.


METHODS
Experimental laboratory in a university teaching hospital.


METHODS
HOCl was infused into the perfusate containing either no inhibitors, ASA (500 micromol/L), or CaA (1 micromol/L).


RESULTS
PAP, pulmonary venous pressure, and ventilation pressure as well as lung weight gain were continuously recorded. Capillary filtration coefficient [Kf,c (10(-4) cm3 x sec(-1) x cm H2O(-1) x g(-1)]) was calculated before and 30, 60, and 90 mins after start of HOCl application. Continuous HOCl application (500, 1000, and 2000 nmol/min) resulted in a time- and dose-dependent increase in Kf,c and PAP with a threshold dose at 500 nmol/min. The onset of these changes was inversely related to the HOCl dose used. Both inhibitors, CaA and ASA, exhibited protective effects on the HOCl-induced alterations in pulmonary microcirculation. ASA predominantly reduced the HOCl-induced pressure response and had a minor but also significant inhibitory effect on edema formation as measured by Kf,c and fluid retention. CaA reduced significantly the rise in Kf,c and subsequent edema formation without effects on pulmonary pressure response.


CONCLUSIONS
Cyclooxygenase and 5-lipoxygenase are involved in oxidative stress induced acute lung injury, suggesting a link between neutrophil-derived oxidative stress and endothelial eicosanoid metabolism.
Wahn
H
H
Department of Cardiology, University of Göttingen, Göttingen, Germany. h.wahn@medizin.uni-wuerzburg.de
Hammerschmidt
S
S
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology*; D002109:Caffeic Acids / Q000494:pharmacology*; D002199:Capillary Permeability / Q000187:drug effects; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D006997:Hypochlorous Acid / Q000494:pharmacology / Q000633:toxicity*; D016859:Lipoxygenase Inhibitors; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D011669:Pulmonary Wedge Pressure / Q000187:drug effects*; D011817:Rabbits
D000975:Antioxidants; D002109:Caffeic Acids; D016861:Cyclooxygenase Inhibitors; D016859:Lipoxygenase Inhibitors; D006997:Hypochlorous Acid; D001241:Aspirin; C040048:caffeic acid