arachidonyltrifluoromethane and Reperfusion-Injury

It is postulated that inhibition of cytosolic phospholipase A(2) alpha (cPLA(2)α) can reduce severity of stroke injury. This is supported by the finding that cPLA(2)α-deficient mice are partially protected from transient, focal cerebral ischemia. The object of this study was to determine the effect of cPLA(2)α inhibition with arachidonyl trifluoromethyl ketone (ATK) on stroke injury in mice. Male C57BL/6 mice were subjected to 1h of focal cerebral ischemia followed by 24 or 72 h of reperfusion. Mice were treated with ATK or vehicle by intermittent intraperitoneal injection or continuous infusion via an implanted infusion pump. ATK injections 1h before and then 1 and 6h after the start of reperfusion significantly reduced infarction volumes in striatum and hemisphere after 24h of reperfusion. ATK did not reduce injury if it was not administered before onset of ischemia or was not administered after 6h of reperfusion. Intermittent doses of ATK failed to reduce infarct volume after 72 h of reperfusion. Continuous infusion with ATK throughout 72h of reperfusion significantly reduced cortical and whole hemispheric infarct volume compared to vehicle treatment. Following ischemia and reperfusion, ATK treatment significantly reduced brain PLA(2) activity. These results are the first to demonstrate a therapeutic effect of cPLA(2)α inhibition on ischemia and reperfusion injury and define a therapeutic time window. cPLA(2)α activity augments injury in the acute and delayed phases of cerebral ischemia and reperfusion injury. We conclude that cPLA(2)α inhibition may be clinically useful if started before initiation of cerebral ischemia.

Topics: Analysis of Variance; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acids; Body Temperature; Brain Infarction; Brain Injuries; Cyclooxygenase 2; Disease Models, Animal; Functional Laterality; Group IV Phospholipases A2; Infarction, Middle Cerebral Artery; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Nitrobenzenes; Reperfusion; Reperfusion Injury; Sulfonamides; Time Factors

Arachidonic acid metabolites and platelet-activating factor (PAF) are potentially involved in ischemia-reperfusion (IR) lung injury. A key enzyme regulating their metabolism is cytosolic phospholipase A2 (cPLA2). Arachidonyl trifluoromethyl ketone (AACOCF3) is reported to be a potent cPLA2 inhibitor. In the present study, we hypothesized that pharmacological inhibition of cPLA2 might ameliorate IR lung injury.. To test the hypothesis, we examined the effects of AACOCF3 in an isolated rat lung model. Three groups were defined (n=6, each): in the vehicle group, lungs were perfused for 2 hours without an ischemic period. In the ischemic groups, 20 mg/kg of AACOCF3 (AACOCF3 group) or saline (control group) was i.v. administered 15 min before lung harvest. Lungs were flushed with LPD solution, cold-stored 18 hours, and reperfused for 2 hours.. IR increased cPLA2 activity mainly via alveolar macrophages, sPLA2 activity, thromboxane and leukotriene formation, and the expression of PAF receptor, whereas AACOCF3 treatment significantly reduced all of these. Compared to the vehicle group, the wet-to-dry ratio, proteins in BAL, and MPO activity increased significantly by twofold, fourfold, and threefold, respectively. Furthermore, the PO2 dropped from 615.7+/-31.2 to 452.1+/-30.9 mmHg at the end of reperfusion (P<0.001). AACOCF3 treatment maintained the PO2 at a level similar to the vehicle group throughout reperfusion and reduced significantly the alveolar-capillary leakage, edema formation, and neutrophil extravasation.. Pharmacological inhibition of the cPLA2 cascade decreases bioactive lipid formation and attenuates IR-induced lung injury.

Topics: Animals; Arachidonic Acids; Disease Models, Animal; Eicosanoids; Group IV Phospholipases A2; Group VI Phospholipases A2; In Vitro Techniques; Lung; Lung Transplantation; Male; Neutrophils; Phospholipases A; Phospholipases A2; Phosphorylation; Platelet Membrane Glycoproteins; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Reperfusion Injury