RESUMO
Free radical species have been implicated as important agents in ischemia-reperfusion injury associated to transplantation procedures. This study was carried out to investigate the possible relationship between phospholipase A2 activity (PLA2), lipoperoxidation, and the changes in arachidonic acid metabolism during ischemia reperfusion injury in pancreas transplantation, as well as the effect of a free radical scavenger such as superoxide dismutase on these changes. For this purpose male Lewis rat groups (n = 7) were classified as follows: group I--control; group II--syngenic pancreas transplantation after 15 min preservation in Collins solution at 4 degrees C; group III--syngenic pancreas transplantation after 18 hr preservation in the same conditions; group IV--same as III but with administration of SOD (i.v.) immediately before revascularization in the recipient rat. The results indicate that significant increases in PLA2 activity and lipoperoxide levels occur concomitantly with an increase of thromboxane B2 (TXB2) and 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) in pancreatic tissue after pancreas transplantation. The counteracting effect of a free radical scavenger such as SOD supports the role of oxygen free radicals (OFR) mediating activation of PLA2 and subsequent formation of eicosanoids in pancreas transplantation.
Assuntos
Ácidos Araquidônicos/metabolismo , Peroxidação de Lipídeos , Transplante de Pâncreas , Pâncreas/metabolismo , Fosfolipases A/análise , Animais , Ácido Araquidônico , Radicais Livres , Masculino , Malondialdeído/análise , Fosfolipases A2 , Ratos , Ratos Endogâmicos Lew , Superóxido Dismutase/farmacologiaAssuntos
Ácidos Araquidônicos/metabolismo , Peroxidação de Lipídeos/fisiologia , Transplante de Pâncreas/fisiologia , Fosfolipases A/metabolismo , Animais , Ácido Araquidônico , Radicais Livres , Masculino , Pâncreas/irrigação sanguínea , Transplante de Pâncreas/efeitos adversos , Fosfolipases A2 , Ratos , Ratos Endogâmicos Lew , Traumatismo por Reperfusão/metabolismo , Superóxido Dismutase/fisiologia , Tromboxano B2/metabolismoRESUMO
A mathematical model has been suggested to describe the kinetics of the prostanoid biosynthesis in the Plexaura homomalla coral. It allows to predict the changes in prostaglandin A2 concentration at various pH and concentration of sodium ions citrate when the latter is not too high. The degradation of prostaglandin biosynthesis intermediates is shown to proceed as two consecutive first-order reactions. For the second step the reaction rate grows into the raise of prostaglandin A2 concentration, apparently due to autocatalytic character of the process.
