Phospholipase A(2) (PLA(2)) activity in mini pigs after acute high dose iv-paraoxon (POX) intoxication

The purpose of the present study was to establish in the mini pig model the effects of paraoxon (POX) on PLA(2) activity. Six anesthetized and mechani cally ventilated mini pigs were infused over 50 min with 0.3, 1, 3, 9, 27 a nd 81 mg POX kg(-1)BW(-1) dissolved in ethanol, respectively. The control a nimal received no POX but the ethanol amount corresponding to the highest P OX dose. PLA(2) activity measurements were carried out immediately after PO X application. Data were analysed with the Mann-Whitney-Wilcoxon rank order test. Statistical significance was assumed for P less than or equal to 0.0 5. Exposure to POX inhibited PLA(2) activity to 50.5 +/- 8.9% of baseline a ctivity. The changes seen were not dose-dependent. The dose dependency prev iously demonstrated in vitro was not reproducible in vivo. This is most pro bably due to the massive endogenous catecholamine release leading to PLA(2) activation. An additional masking effect is due to the (co)administration of drugs needed for anesthesia and cardiovascular support, especially Mg2+. These substances also influence the PLA(2) activity. (C) 1999 Elsevier Sci ence Ireland Ltd. All rights reserved.