RESUMO
Weanling rats fed a methyl-deficient diet develop acute renal failure, the morphological features of which vary from focal tubular necrosis to widespread cortical necrosis. We and others have shown that coconut oil, rich in saturated fatty acids, has a renal protective effect in this experimental model. In the experiment we are reporting now, we studied which fatty acid is involved in the protection afforded by coconut oil by feeding five groups of methyl-deficient rats a mixture of corn oil and hydrogenated vegetable oil, C6-C8-C10 fatty acids, C12 fatty acid, C14 fatty acid and C16-C18 fatty acids. Five groups of rats receiving the same diets supplemented with choline chloride were used as controls. The group of methyl-deficient rats fed C14 fatty acid (myristic acid) showed a greater percentage of surviving animals and lower renal damage than the other groups of methyl-deficient rats, indicating that the protective effect of coconut oil found in previous experiments is due to its high content of myristic acid.
Assuntos
Deficiência de Colina/complicações , Dieta , Necrose do Córtex Renal/prevenção & controle , Ácido Mirístico/farmacologia , Análise de Variância , Animais , Peso Corporal , Deficiência de Colina/patologia , Creatinina/sangue , Necrose do Córtex Renal/etiologia , Necrose do Córtex Renal/patologia , Masculino , Tamanho do Órgão , Ratos , Ratos Wistar , Ureia/sangueRESUMO
Fenofibrate, the hypolipidemic drug and peroxisome proliferator, was given to mice (0.23% w/w in the diet) during 1-3 weeks and H2O2 and TBARS steady state concentrations, liver chemiluminescence and antioxidant levels were measured. Administration of fenofibrate during 2 weeks induced an increase of 89% in H2O2 steady state concentration. Spontaneous chemiluminescence was decreased by 57% during fenofibrate treatment, while no significant effect was observed on TBARS concentration. Hydroperoxide-initiated chemiluminescence was decreased by 56% after 15 days of fenofibrate treatment, probably due to an increase in endogenous antioxidant levels. Total and oxidized glutathione increased gradually after fenofibrate administration, obtaining maximal increases of 67% and 58% respectively, after 22 days of treatment. An increase of 55% was found in ubiquinol levels in treated mice, as compared with the controls. alpha-tocopherol content was decreased by 51% in the liver of fenofibrate-treated mice. According to our findings, the high rate of H2O2 production associated with peroxisome proliferation, would not lead to an increase in lipid peroxidation. This can be explained by the presence of high levels of ubiquinols, which act as an antioxidant. The increased production of H2O2, would lead to DNA damage directly, and not through lipid peroxidation processes.
Assuntos
Antioxidantes/análise , Fenofibrato/administração & dosagem , Hipolipemiantes/administração & dosagem , Fígado/efeitos dos fármacos , Microcorpos/efeitos dos fármacos , Animais , Dano ao DNA , Feminino , Glutationa/análise , Peróxido de Hidrogênio/análise , Peroxidação de Lipídeos , Fígado/metabolismo , Fígado/ultraestrutura , Medições Luminescentes , Camundongos , Microcorpos/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/análiseRESUMO
Acetaminophen was given to mice at a single dose of 375 mg/kg. In situ liver chemiluminescence, H2O2 steady-state concentration, and the liver concentrations of total and oxidized glutathione were measured 15, 30, and 60 min after acetaminophen administration. Increases of 145% and 72% in spontaneous chemiluminescence and H2O2 concentration were observed 15 min after the injection, respectively. Total glutathione was decreased by acetaminophen administration at all the times studied. The maximal decrease, 83%, was found 60 min postinjection. The ratio GSH/GSSG was found significantly decreased at all the times studied. Microsomal superoxide production was increased by 2.4-fold by addition of acetaminophen. The activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase were determined. Catalase was slightly inhibited (30%) 15 min after acetaminophen administration. No significant changes were found in superoxide dismutase activity. Se and non-Se glutathione peroxidase activities were decreased by 40% and 53% respectively, 15 min after acetaminophen administration. The decrease in catalase and glutathione peroxidase would result in an increased steady state level of H2O2 and hydroperoxides, contributing to cell injury. Damaged hepatocytes were observed, and severe lesions and necrosis appeared 60 min after acetaminophen administration. Our results indicate the occurrence of oxidative stress as a possible mechanism for acetaminophen-induced hepatotoxicity.
Assuntos
Acetaminofen/toxicidade , Fígado/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/toxicidade , Alanina Transaminase/sangue , Animais , Aspartato Aminotransferases/sangue , Relação Dose-Resposta a Droga , Feminino , Glutationa/análogos & derivados , Glutationa/metabolismo , Dissulfeto de Glutationa , Peróxido de Hidrogênio/metabolismo , Cinética , L-Lactato Desidrogenase/sangue , Fígado/efeitos dos fármacos , Fígado/patologia , Medições Luminescentes , Camundongos , Superóxidos/metabolismoRESUMO
We have studied microsomal phospholipid, cholesterol and protein concentration in rat renal papilla, medulla and cortex during postnatal development, and the relationship between these membranes biochemical parameters and morphological changes. We also determined DNA concentration in each kidney zone. No changes were observed either in papillary microsomal phospholipids, proteins and cholesterol or in DNA concentration from 10-to 70-day-old rats. Medullary microsomal proteins and cholesterol did not change but a significant increase was observed in the microsomal phospholipid concentration during development; in this case, medullary DNA was significantly lower at 70 than at 10 days. In contrast, all biochemical parameters in renal cortex were significantly higher during development except for DNA concentration which suffered a great decrease. These biochemical findings demonstrate that the developmental pattern is different in each zone of the kidney and confirm the fact that the papilla, in newborn rats, is almost fully developed whereas the renal cortex and medulla are immature.
Assuntos
Envelhecimento/metabolismo , Rim/crescimento & desenvolvimento , Rim/metabolismo , Animais , Animais Recém-Nascidos , Colesterol/metabolismo , DNA/metabolismo , Rim/citologia , Microssomos/metabolismo , Índice Mitótico , Fosfolipídeos/metabolismo , Proteínas/metabolismo , Ratos , Ratos Wistar , Distribuição TecidualRESUMO
In this article the spontaneous chemiluminescence and the steady-state concentration of hydrogen peroxide were determined in rat liver as indicators of oxidative stress in the tissue. Hydroperoxide-initiated chemiluminescence and the activity of antioxidant enzymes (catalase, superoxide dismutase and glutathione peroxidase) were also measured to evaluate antioxidant defenses and serum activity of lactate dehydrogenase and aspartate aminotransferase. Mitochondrial morphology and mitochondrial respiratory control ratio were measured as indicators of cell and mitochondrial damage. Xanthine dehydrogenase and xanthine oxidase activities were determined as a possible source of oxyradicals. No significant changes were observed after 10 or 30 min of vena cava occlusion in any of the measured parameters. In contrast, 10 min of occlusion followed by 10 min of reperfusion increased chemiluminescence (from 18 +/- 3 to 32 +/- 5 cps/cm2), hydrogen peroxide (from 0.10 +/- 0.01 to 0.17 +/- 0.01 mumol/L), lactate dehydrogenase (from 80 +/- 2 to 330 +/- 30 U/L), and aspartate aminotransferase (from 42 +/- 2 to 100 +/- 10 U/L). Liver reperfusion was also associated with mitochondrial swelling and decreased mitochondrial respiratory control (from 5.6 +/- 0.3 to 2.6 +/- 0.1). The activity of the antioxidant enzymes and xanthine oxidase was instead without change. After 30 min of vena cava occlusion and 10 min of reperfusion a more marked increase in chemiluminescence (37 +/- 5 cps/cm2), hydrogen peroxide (0.30 +/- 0.01 mumol/L), lactate dehydrogenase (730 +/- 10 U/L) and aspartate aminotransferase (140 +/- 10 U/L) was observed. No further changes were found in either mitochondrial morphology or respiratory control (2.4 +/- 0.1) in isolated mitochondria.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Fígado/metabolismo , Oxigênio/metabolismo , Reperfusão , Veia Cava Inferior , Animais , Aspartato Aminotransferases/metabolismo , Constrição , Peróxido de Hidrogênio/metabolismo , L-Lactato Desidrogenase/metabolismo , Medições Luminescentes , Masculino , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/patologia , Dilatação Mitocondrial , Oxirredução , Oxirredutases/metabolismo , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Traumatismo por Reperfusão/metabolismoRESUMO
The time course of oxidative stress and tissue damage in zonal liver ischemia-reperfusion in rat liver in vivo was evaluated. After 180 min of ischemia, surface chemiluminescence decreased to zero, state 3 mitochondrial respiration decreased by 70-80%, and xanthine oxidase activity increased by 26% without change in the water content and in the activities of superoxide dismutase, catalase, and glutathione peroxidase. After reperfusion, marked increases in oxyradical production and tissue damage were detected. Mitochondrial oxygen uptake in state 3 and respiratory control as well as the activities of superoxide dismutase, catalase, and glutathione peroxidase and the level of nonenzymatic antioxidants (evaluated by the hydroperoxide-initiated chemiluminescence) were decreased. The severity of the post-reperfusion changes correlated with the time of ischemia. Morphologically, hepatocytes appeared swollen with zonal cord disarrangement which ranged from mild to severe for the tissue reperfused after 60-180 min of ischemia. Neutrophil infiltration was observed after 180 min of ischemia and 30 min of reperfusion. Mitochondria appear as the major source of hydrogen peroxide in control and in reperfused liver, as indicated by the almost complete inhibition of hydrogen peroxide production exerted by the uncoupler carbonylcyanide p-(trifluoromethoxy) phenylhydrazone. Additionally, inhibition of mitochondrial electron transfer by antimycin in liver slices reproduced the inhibition of state 3 mitochondrial respiration and the increase in hydrogen peroxide steady-state concentration found in reperfused liver. Increased rates of oxyradical production by inhibited mitochondria appear as the initial cause of oxidative stress and liver damage during early reperfusion in rat liver.
Assuntos
Peróxido de Hidrogênio/metabolismo , Isquemia/metabolismo , Fígado/irrigação sanguínea , Traumatismo por Reperfusão/metabolismo , Animais , Radicais Livres , Fígado/metabolismo , Fígado/patologia , Medições Luminescentes , Masculino , Mitocôndrias Hepáticas/metabolismo , Consumo de Oxigênio , Fenobarbital/farmacologia , Ratos , Ratos Wistar , Xantina Desidrogenase/metabolismo , Xantina Oxidase/metabolismoRESUMO
Seventeen patients with coronary disease submitted to myocardial revascularization were studied. Ten patients had a hypertrophied ventricle, and 7 had normal ventricular mass. Myocardial biopsies were obtained before ischemia and at the time of reperfusion and were assessed for: volume fraction of fibrous tissue, myocyte diameter, morphometric mitochondrial studies and ultrastructural changes. The volume fraction of fibrous tissue in patients with hypertrophied ventricle was 1.9 +/- 0.04, and in patients with normal ventricular mass was 0.9 +/- 0.01 (p less than 0.05). The diameter of the myocyte was 23 +/- 0.3 microns and 18 +/- 1.2 microns for patients with hypertrophied and normal ventricular mass, respectively (p less than 0.01). The value of volumetric density for pre-ischemia samples in patients with a hypertrophied ventricle was 23 +/- 2.2 and in patients with normal ventricular mass was 35 +/- 2.7 (p less than 0.02). Grades 3 and 4 of damaged mitochondria were significantly increased in reperfusion samples from patients with a hypertrophied ventricle compared to pre-ischemia samples. Collagen growth was increased in hypertrophied hearts which were also more sensitive to the ischemia/reperfusion mechanism.