Purpose To investigate the effects of induction of selective liver hypothermia in a rodent model. Methods Seven male Wistar rats were subjected to 90 minutes of partial 70% liver ischemia and topic liver 26°C hypothermia (H group). Other seven male Wistar rats were subjected to 90 minutes of partial 70% normothermic liver ischemia (N group). Five additional rats underwent a midline incision and section of liver ligaments under normothermic conditions and without any liver ischemia (sham group). All animals were sacrificed 24-h after reperfusion, and livers were sampled for analyses. Pathology sections were scored for sinusoidal congestion, ballooning, hepatocelllular necrosis and the presence of neutrophilic infiltrates. Results At the end of the experiment, liver tissue expressions of TNF-ɑ, IL-1β, iNOS and TNF-ɑ/IL-10 ratio were significantly reduced in the H group compared to N group, whereas IL-10 and eNOS were significantly increased in H group. Histopathological injury scores revealed a significant decrease in ischemia/reperfusion (I/R) injuries in H group. Conclusion Selective liver hypothermia prevented I/R injury by inhibiting the release of inflammatory cytokines, preserves microcirculation, prevents hepatocellular necrosis and leukocyte infiltration, allowing maintenance of the liver architecture.

PURPOSE:To design an animal model of ischemia-reperfusion (I/R) in kidneys and evaluate the role that predetermined ranges of local hypothermia plays on markers of stress-oxydative as well as on histologic sections. METHODS: Twenty eight male rats Wistar, under general anesthesia, undergone right nephrectomy (G0, control group) followed by left kidney ischemia during 40 min. Four temperatures groups were designed, with seven animals randomized for each group: normothermic (G1, ±37ºC), mild hypothermia (G2, 26ºC), moderate hypothermia (G3, 15ºC) and deep hypothermia (G4, 4ºC). Left kidney temperature was assessed with an intraparenchymal probe. Left nephrectomy was performed after 240 min of reperfusion. After I/R a blood sample was obtained for f2-IP. Half of each kidney was sent to pathological evaluation and half to analyze CAT, SOD, TBARS, NO3, NO2. RESULTS:Histopathology showed that all kidneys under I/R were significantly more injured than the G0 (p<0.001). TBARS had increased levels in all I/R groups compared with the G0 (p<0.001). CAT had a significant difference (p<0.03) between G1 and G4. Finally, no difference was found on SOD, NO3, NO2 nor on f2-IP. CONCLUSION: This model of I/R was efficient to produce oxidative-stress in the kidney, showing that 4ºC offered significant decrease in free radicals production, although tissue protection was not observed.

OBJETIVO: Avaliar os efeitos da hipotermia hepática tópica combinada ao pré-condicionamento isquêmico na proteção dos danos iniciais de isquemia e reperfusão. MÉTODOS: Trinta e dois ratos Wistar foram submetidos à isquemia hepática parcial durante 90 minutos em Normotermia (IN), Pré-condicionamento Isquêmico (IPC), Hipotermia a 26ºC (H) e Hipotermia a 26ºC mais PCI (H+PCI). A PAM, a temperatura corporal e o fluxo biliar foram aferidos em intervalos de 15 minutos. Marcadores plasmáticos de danos hepáticos e as defesas antioxidantes foram avaliados após 120 minutos de reperfusão. RESULTADOS: A PAM e a temperatura corporal permaneceram constantes durante o experimento. O fluxo biliar retornou a valores semelhantes ao grupo C nos grupos H e H+PCI após 45 minutos de reperfusão e aumentou significativamente nos grupos H e H+PCI em comparação aos grupos IN e PCI após 105 e 120 minutos. Os níveis plasmáticos da AST e ALT demonstraram aumento significativo no grupo IN em comparação ao grupo C. Os níveis de TBARS diminuíram significativamente no grupo H+PCI em comparação aos grupos IN, PCI e H. Os níveis de Catalase aumentaram significativamente no grupo PCI em comparação aos grupos C, IN e H+PCI. Os níveis de SOD foram significativamente maiores no grupo H em comparação aos grupos C, IN, PCI e H+PCI. CONCLUSÃO: A hipotermia tópica protegeu o fígado isquêmico contra os danos de isquemia e reperfusão e permitiu uma recuperação precoce da função hepática.

PURPOSE: To evaluate the effects of the topical liver hypothermia and IPC combination against I/R injury after initial reperfusion. METHODS: In 32 Wistar rats, partial liver ischemia was induced for 90 minutes in normothermia (IN), ischemic preconditioning (IPC), 26ºC topical hypothermia (H) and 26ºC topical hypothermia plus IPC (H+IPC). MAP, body temperature and bile flow were recorded each 15 minutes. Plasmatic injury markers and tissue antioxidant defenses were assessed after 120 minutes of reperfusion. RESULTS: MAP and body temperature remained constant during all experiment. Bile flow returned to levels similar to controls after 45 minutes of reperfusion in the H and H+IPC groups and increased significantly in comparison to the NI and IPC groups after 105 and 120 minutes. AST and ALT increased significantly in the normothermic groups in comparison to controls. TBARS levels decreased significantly in the H+IPC group in comparison to the other groups whereas Catalase levels increased significantly in the IPC group. SOD levels were significantly higher in the H group in comparison to all groups. CONCLUSION: The induction of 26ºC topical hypothermia associated or not to IPC protected the ischemic liver against ischemia/reperfusion injuries and allowed an early recovery of the hepatic function.

OBJETIVO: Avaliar as variações de temperatura corporal, pressão arterial média (PAM) em um novo modelo de isquemia e reperfusão hepático que utiliza Pré-condicionamento isquêmico e Hipotermia tópica. MÉTODOS: Ratos (n= 32) da raça Wistar foram divididos em 5 grupos: Controle (C), Isquemia normotérmica (IN), Hipotermia a 26°C (H), Pré-condicionamento isquêmico (PCI) e Hipotermia a 26°C com Pré-condicionamento isquêmico com hipotermia (H+PCI). As aferições da PAM e temperatura corporal foram realizadas em intervalos de 30 minutos. Os animais foram submetidos à isquemia hepática de 90 minutos e 120 minutos de reperfusão. Nos grupos H e H+PCI, o fígado foi isolado e resfriado por superfusão de solução fisiológica gelada. Nos grupos com PCI e H+PCI foram aplicados 10 minutos de isquemia e 10 minutos de reperfusão antes do insulto isquêmico maior. RESULTADOS: Não houve diferença na PAM e temperatura corporal entre os grupos durante todo o experimento. CONCLUSÃO: O presente modelo permite a aplicação de hipotermia local associada ou não ao PCI. Novos estudos para avaliar os possíveis efeitos sinergísticos destas ferramentas podem ser reproduzidos sem alterações significativas na macrohemodinâmica e temperatura corporal, ou seja, sob condições estáveis.

PURPOSE: Evaluation of the Mean Arterial Pressure (MAP) and body temperature changes in a new model of liver ischemia-reperfusion applying topical Hypothermia and Ischemic Preconditioning (IPC). METHODS: Rats (n= 32) were divided in 5 groups: Control (C), Normothermic Ischemia (NI), Ischemic Preconditioning (IPC), Hypothermia 26°C plus IPC (H+IPC) and Hypothermia 26°C (H). MAP and body temperature were recorded at 30 minutes intervals throughout the entire experiment. The study groups underwent 90 minutes partial hepatic ischemia followed by 120 minutes of reperfusion. The median and lateral left lobes were isolated and topical 26°C hypothermia was induced by superfusion of cooled saline solution in H+IPC and H groups. A 10 minutes protocol of ischemia and reperfusion was applied in the IPC and H+IPC groups before the major ischemic insult. RESULTS: There was no significant difference in MAP and body temperature means between the groups throughout the experiments. CONCLUSION: The present model allows the induction of topical hepatic hypothermia associated or not to IPC. New studies to evaluate the possible synergistic effects of these tools can be reproduced without significant changes in macrohemodynamics and body temperature, or in other words, under stable conditions.

OBJETIVO: O estresse oxidativo é um importante mecanismo responsável pela disfunção dos enxertos após transplante de fígado (TF). Sabe-se que níveis baixos de Glutationa reduzida (GSH) deixam os enxertos vulneráveis aos danos de reperfusão. O objetivo deste estudo foi avaliar as concentrações de GSH e da Glutationa oxidada (GSSG), os danos hepatocelulares e a função em enxertos ótimos e subótimos após TF. MÉTODOS: Foram realizadas biópsias em 33 pacientes imediatamente antes do implante e duas horas após a reperfusão, permitindo a determinação do GSH, GSSG e o cálculo do índice de stress oxidativo (GSH/GSSG). Foram medidas as transaminases hepáticas e as atividades da Protrombina (TP) e do Fator V para avaliação dos danos hepatocelulares e da função do enxerto, respectivamente. O dano histopatológico foi avaliado através de um índice de cinco parâmetros. RESULTADOS: Houve uma diminuição nos níveis de GSH (p<0.01) 0.323 ± 0.062 ìmol/g to 0.095 ± 0.01 ìmol/g and 0.371 ± 0.052 ìmol/g to 0.183 ± 0.046 ìmol/g) e aumento nos níveis de GSSG (0.172 ± 0.038 ìmol/g to 0.278 ± 0.077 ìmol/g and 0.229 ± 0.048 ìmol/g to 0.356 ± 0.105 ìmol/g) (p<0.05). Houve diminuição do GSH/GSSG (2.23 ± 0.31 to 0.482 ± 0.042 and 2.47 ± 0.32 to 0.593 ± 0.068). Nenhuma diferença entre os grupos ótimo e subótimo foi vista após duas horas de reperfusão. Os escores de danos histopatológicos foram maiores no grupo subótimo (6.46 ± 0.4 vs. 5.39 ± 1.1) (p<0.05) e mostraram correlação com o TP e fator V no grupo Ótimo (p<0.05). A análise multivariada apontou a esteatose como um fator de risco independente para a ocorrência de danos histopatológicos (p<0.05). CONCLUSÃO: Houve uma significativa depleção de GSH e formação de GSSG após a preservação em solução devido a um intenso estresse oxidativo nos enxertos ótimos e subótimos, porém estes níveis não se correlacionaram com a viabilidade dos enxertos.

PURPOSE: The oxidative stress is an important mechanism responsible for dysfunction after orthotopic liver transplantation (OLT). Glutathione (GSH) low levels after cold storage render the grafts vulnerable to reperfusion injury. Aim of this study was to evaluate GSH and oxidized glutathione (GSSG) liver concentrations, the hepatocellular injury and function in optimal and suboptimal grafts after human OLT. METHODS: Liver biopsies were taken in 33 patients before the implant and two hours after reperfusion, allowing determination of GSH, GSSG and oxidative stress ratio (GSH/GSSG). Serum transaminases, prothrombin activity (PT) and factor V were measured to evaluate injury and function respectively. Histopathological injury was analyzed by an index of five parameters. RESULTS: There was a decrease in GSH (p<0.01) after reperfusion (0.323 ± 0.062 ìmol/g to 0.095 ± 0.01 ìmol/g and 0.371 ± 0.052 ìmol/g to 0.183 ± 0.046 ìmol/g) in suboptimal and optimal groups, respectively. An increase of GSSG (p<0.05) occurred after reperfusion (0.172 ± 0.038 ìmol/g to 0.278 ± 0.077 ìmol/g and 0.229 ± 0.048 ìmol/g to 0.356 ± 0.105 ìmol/g) in suboptimal and optimal groups, respectively. A decrease (p<0.01) occurred in the GSH/GSSG ratio after reperfusion (2.23 ± 0.31 to 0.482 ± 0.042 and 2.47 ± 0.32 to 0.593 ± 0.068) in suboptimal and optimal groups, respectively. Histopathological injury scores were higher (p<0.05) in the suboptimal group than in optimal (6.46 ± 0.4 vs. 5.39 ± 1.1) and showed correlation with PT and factor V in the optimal group (p<0.05). Multivariate analysis pointed steatosis as an independent risk factor to histopathological injury (p<0.05). CONCLUSION: There was a significant GSH depletion and GSSG formation after cold storage and reperfusion due to a similar oxidative stress in optimal and suboptimal grafts, but these levels were not related to graft viability.