RESUMEN
BACKGROUND: Postmenopausal hormone replacement therapy (HRT) relieves menopausal symptoms and may decrease mortality in recently postmenopausal women, but increases breast cancer risk. Low-dose tamoxifen has shown retained activity in phase-II studies. METHODS: We conducted a phase-III trial in 1884 recently postmenopausal women on HRT who were randomly assigned to either tamoxifen, 5 mg/day, or placebo for 5 years. The primary end point was breast cancer incidence. RESULTS: After 6.2 ± 1.9 years mean follow-up, there were 24 breast cancers on placebo and 19 on tamoxifen (risk ratio, RR, 0.80; 95% CI 0.44-1.46). Tamoxifen showed favorable trends in luminal-A tumors (RR, 0.32; 95% CI 0.12-0.86), in HRT users <5 years (RR, 0.35; 95% CI 0.15-0.82) and in women completing at least 12 months of treatment (RR, 0.49; 95% CI 0.23-1.02). Serious adverse events did not differ between placebo and tamoxifen, including, respectively, coronary heart syndrome (6 versus 4), cerebrovascular events (2 versus 5), VTE (2 versus 5) and uterine cancers (3 versus 1). Vasomotor symptoms were 50% more frequent on tamoxifen. CONCLUSIONS: The addition of low-dose tamoxifen to HRT did not significantly reduce breast cancer risk and increased climacteric symptoms in recently postmenopausal women. However, we noted beneficial trends in some subgroups which may deserve a larger study.
Asunto(s)
Neoplasias de la Mama/tratamiento farmacológico , Terapia de Reemplazo de Hormonas/efectos adversos , Tamoxifeno/administración & dosificación , Neoplasias de la Mama/patología , Climaterio/efectos de los fármacos , Cálculo de Dosificación de Drogas , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/clasificación , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/patología , Femenino , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Posmenopausia , Tamoxifeno/efectos adversosRESUMEN
The effects of cryoprotectants, cooling rate and freezing on the mussel Mytilus galloprovincialis sperm were evaluated. At the end of each step of the experimental protocol, motility and fertilization ability of sperm were analyzed, compared to fresh semen. Five cryoprotectants were tested in their toxicity level: dimethylsulfoxide, ethylene glycol, 1-2 propylene glycol at 5%, 7%, 10%, 15% and 20% concentration; glycerol and methanol at concentration of 5%, 7% and 10%. The incubation times were 10, 20 and 30 min at 20+/-1 degrees C. Only dimethylsulfoxide, ethylene glycol and 1-2 propylene glycol at 5%, 7% and 10% were chosen for the following pre-freezing step. Five adaptation/chilling rates were analyzed: 10 min at 20+/-1, -2, -1, -0.5 and -0.25 degrees C/min and the last one was used for testing the best freezing procedure among seven gradients. Particularly, two rapid rates, three slow rates and two double step rates were conducted. Thawing results showed that M. galloprovincialis sperm are very sensitive to rapid pre-freezing and freezing protocols and only a slow procedure assured good motility and fertilization percentages.
Asunto(s)
Criopreservación/métodos , Crioprotectores/farmacología , Mytilus , Preservación de Semen/métodos , Animales , Crioprotectores/química , Crioprotectores/toxicidad , Fertilización In Vitro/efectos de los fármacos , Masculino , Motilidad Espermática/efectos de los fármacos , Espermatozoides/efectos de los fármacos , Espermatozoides/fisiologíaRESUMEN
BACKGROUND: Triplet regimens were occasionally reported to produce a higher response rate (RR) than doublets in locally advanced or metastatic non-small-cell lung cancer (NSCLC). This trial was conducted to assess (i) whether the addition of cisplatin (CDDP) to either gemcitabine (GEM) and vinorelbine (VNR) or GEM and paclitaxel (PTX) significantly prolongs overall survival (OS) and (ii) to compare the toxicity of PTX-containing and VNR-containing combinations. PATIENTS AND METHODS: Stage III or IV NSCLC patients were randomly assigned to (i) GEM 1000 mg/m(2) and VNR 25 mg/m(2) on days 1 and 8 (GV arm); (ii) GEM 1000 mg/m(2) and PTX 125 mg/m(2) on days 1 and 8 (GT arm); (iii) GV plus CDDP 50 mg/m(2) on days 1 and 8 (PGV arm); and (iv) GT plus CDDP 50 mg/m(2) on days 1 and 8 (PGT arm). Treatments were repeated every 3 weeks for a maximum of six cycles. RESULTS: A total of 433 (stage III, 160; stage IV, 273) patients were randomly allocated to the study. RR was 48% [95% confidence interval (CI), 42% to 54%] for triplets and 35% (95% CI, 32% to 38%) for doublets (P = 0.004). Median progression-free survival (6.1 versus 5.5 months, P = 0.706) and median OS (10.7 versus 10.5 months, P = 0.379) were similar. CDDP significantly increased the occurrence of severe neutropenia (35% versus 13%), thrombocytopenia (14% versus 4%), anaemia (9% versus 3%), vomiting (6% versus 0.5%), and diarrhoea (6% versus 2%). Conversely, frequency of severe neutropenia (30% versus 17%) and thrombocytopenia (11% versus 6%) was significantly higher with VNR-containing regimens. CONCLUSIONS: Adding CDDP to GV or GT significantly increased RR, but did not prolong the OS of patients. Among doublets, the GT regimen should be preferred in view of its better safety profile.
Asunto(s)
Adenocarcinoma/tratamiento farmacológico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Células Grandes/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Células Escamosas/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Adenocarcinoma/secundario , Adulto , Anciano , Carcinoma de Células Grandes/secundario , Carcinoma de Pulmón de Células no Pequeñas/patología , Carcinoma de Células Escamosas/secundario , Desoxicitidina/administración & dosificación , Desoxicitidina/análogos & derivados , Femenino , Humanos , Italia , Neoplasias Pulmonares/patología , Masculino , Persona de Mediana Edad , Paclitaxel/administración & dosificación , Pronóstico , Tasa de Supervivencia , Vinblastina/administración & dosificación , Vinblastina/análogos & derivados , Vinorelbina , GemcitabinaRESUMEN
The aim of this research was to optimise protocols for freezing spermatozoa of the Pacific oyster. All the phases of the cryopreservation procedure (choice of cryoprotectant, cooling, freezing, and thawing) were studied in relation to the species of spermatozoa to restore on thawing the morphological and physiological characteristics of fresh semen. The choice of type and concentration of cryoprotectant in which semen is incubated before freezing is fundamental for a successful cryopreservation: the cryoprotectants (dimethylsulfoxide--Me(2)SO, ethylene glycol--EG, propylene glycol-PG, and glycerol in concentrations between 5 and 15%) were tested for their toxicity on the semen exposed up to 30 min at +26 degrees C (room temperature) by evaluating its ability to fertilise and the embryo development to the regular D larval stage. The best cryoprotectants, Me(2)SO, EG, and PG 5, 10, and 15% respectively, were used for the pre-cooling (adaptation/cooling) tests. Two different adaptation/cooling procedures were tested: (A) from +26 degrees C to 0-2 degrees C (2.6 degrees C/min) and (B) at +26 degrees C for 15 min. Lastly, using the cryoprotectants and the adaptation procedure (B) that had given the best results in the preceding stages of the experiment, four cooling rates were tested: 6, 11, 16, and 21 degrees C/min. It was seen that the semen that was incubated with EG 10%, adapted at +26 degrees C for 15 min, and then cooled at a rate of 6 degrees C/min showed a percentage of regular D larvae on thawing comparable to that of fresh semen (p > 0.05).
Asunto(s)
Criopreservación/métodos , Crioprotectores/farmacología , Fertilización , Preservación de Semen/métodos , Espermatozoides/metabolismo , Animales , Frío , Dimetilsulfóxido/química , Glicol de Etileno/química , Femenino , Congelación , Masculino , Ostreidae , Propilenglicol/química , Semen , Espermatozoides/patología , Temperatura , Factores de TiempoRESUMEN
This study was designed to investigate the short-term effects of cortisol and 17-beta-estradiol on the intact coronary tree of rainbow trout (Oncorhynchus mykiss). A non-working, isolated, and perfused heart preparation was used. The coronary pressure was monitored together with the coronary flow in order to calculate the coronary resistance. The drug effects were expressed as percent change in coronary resistance. At concentrations higher than 10(-5) mol l(-1), cortisol elicited a significant vasoconstriction (p<0.001) within 10 min of perfusion. The simultaneous administration of cortisol and adenosine (both at 10(-4) mol l(-1)) induced a significant reduction (p<0.001) of the coronary tree response elicited by each drug alone. The perfusion of the intact coronary trout system with 20 ng ml(-1) of 17-beta-estradiol elicited a significant vasodilative response (p<0.001) within 5-15 min of perfusion. This vasodilation did not involve nitric oxide, because no significant effect of Nomega-nitro-L-arginine (L-NA, a nitric oxide synthase inhibitor) in presence of the estrogen was observed. 17-beta-estradiol was also able to reduce the vasoconstriction induced by 10(-3) mol l(-1) acetylcholine. From these results it is possible to suggest that the steroid hormones, cortisol and 17-beta-estradiol, expound their action on the trout coronary tree through a non-genomic mechanism.
Asunto(s)
Antiinflamatorios/farmacología , Circulación Coronaria/efectos de los fármacos , Estradiol/farmacología , Hidrocortisona/farmacología , Oncorhynchus mykiss/fisiología , Animales , Interacciones Farmacológicas , Inhibidores Enzimáticos/farmacología , Femenino , Técnicas In Vitro , Masculino , Óxido Nítrico/metabolismo , Nitroarginina/farmacología , Resistencia Vascular/efectos de los fármacos , Vasodilatación/efectos de los fármacosRESUMEN
We investigated the effects of ischemia duration on the functional response of mitochondria to reperfusion and its relationship with changes in mitochondrial susceptibility to oxidative stress. Mitochondria were isolated from hearts perfused by the Langendorff technique immediately after different periods of global ischemia or reperfusion following such ischemia periods. Rates of O2 consumption and H2O2 release with complex I- and complex II-linked substrates, lipid peroxidation, overall antioxidant capacity, capacity to remove H2O2, and susceptibility to oxidative stress were determined. The effects of ischemia on some parameters were time dependent so that the changes were greater after 45 than after 20 min of ischemia, or were significantly different to the nonischemic control only after 45 min of ischemia. Thus, succinate-supported state 3 respiration exhibited a significant decrease after 20 min of ischemia and a greater decrease after 45 min, while pyruvate malate-supported respiration showed a significant decrease only after 45 min of ischemia, indicating an ischemia-induced early inhibition of complex II and a late inhibition of complex I. Furthermore, both succinate and pyruvate malate-supported H2O2 release showed significant increases only after 45 min of ischemia. Similarly, whole antioxidant capacity significantly increased and susceptibility to oxidants significantly decreased after 45 min of ischemia. Such changes were likely due to the accumulation of reducing equivalents, which are able to remove peroxides and maintain thiols in a reduced state. This condition, which protects mitochondria against oxidants, increases mitochondrial production of oxyradicals and oxidative damage during reperfusion. This could explain the smaller functional recovery of the tissue and the further decline of the mitochondrial function after reperfusion following the longer period of oxygen deprivation.
Asunto(s)
Mitocondrias/fisiología , Isquemia Miocárdica , Reperfusión Miocárdica , Estrés Oxidativo , Animales , Relación Dosis-Respuesta a Droga , Peróxido de Hidrógeno/metabolismo , Peroxidación de Lípido , Malatos/metabolismo , Masculino , Mitocondrias/metabolismo , Consumo de Oxígeno , Unión Proteica , Piruvatos/metabolismo , Ratas , Ratas Wistar , Factores de TiempoRESUMEN
The effects of low-intensity, prolonged swimming on functional recovery of the rat heart (Langendorff preparations) from ischaemia-reperfusion (I/R) were investigated. Three groups of rats (120 days old) were used: sedentary rats (S) and rats exercised by a single bout of swimming lasting 5 (E5) or 8 h (E8), respectively. The effect of exercise on the response to I/R was related to an index of oxidative damage such as lipid peroxidation, as well as to the tissue antioxidant capacity and the response of heart tissue to in vitro oxidative stress. The intrinsic performance of E5 Langendorff preparations paced at 220 beats x min(-1) was also determined. A group of sedentary animals was used for H2O2-treated preparations. The effect of antioxidant treatment on inotropic recovery during reperfusion was studied on preparations from 5 or 8 h swimming vitamin E-treated (EVT5 and EVT8 and 5 or 8 h swimming untreated (EVU5 and EVU8) rats. Hearts from exercised animals displayed a reduced preischaemic inotropism, which in E5 rats was accompanied by an increase in the intrinsic heart rate. The lower intrinsic cardiac inotropism of E5 animals was confirmed in the paced preparations. The reduced contractility found in control hearts after addition of H2O2 to perfusion medium suggested that the low inotropism of E5 and E8 hearts was due to an exercise-induced increase in reactive oxygen species. Inotropic recovery during reperfusion was low in the S hearts, was significantly increased in the E5 hearts, and was again reduced to the S level in the E8 hearts. In the E8 hearts the indexes of cellular damage (LDH release) and oxidative stress increased, and antioxidant capacity decreased, while in E5 hearts there was no evidence of significant changes in such parameters. Performance and reperfusion recovery of hearts from 5 h swimming rats was not affected by vitamin E treatment, while those of hearts from 8 h swimming rats was the highest observed. We suggest that the higher inotropic recovery during reperfusion in the hearts from the E5 rats is related to the negative inotropic effect of exercise. The fall in recovery following the 8 h exercise was instead related to the increased oxidative stress.
Asunto(s)
Isquemia Miocárdica/metabolismo , Isquemia Miocárdica/fisiopatología , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/fisiopatología , Condicionamiento Físico Animal/fisiología , Animales , Antioxidantes/metabolismo , Frecuencia Cardíaca/fisiología , Peróxido de Hidrógeno/farmacología , L-Lactato Deshidrogenasa/metabolismo , Peroxidación de Lípido/efectos de los fármacos , Peroxidación de Lípido/fisiología , Masculino , Miocardio/enzimología , Miocardio/patología , Tamaño de los Órganos , Oxidantes/farmacología , Estrés Oxidativo/efectos de los fármacos , Estrés Oxidativo/fisiología , Marcapaso Artificial , Ratas , Ratas Wistar , Recuperación de la Función/fisiología , Natación/fisiología , Presión Ventricular/fisiología , Vitamina E/farmacologíaRESUMEN
The capacity of rat liver homogenates and mitochondria to remove H(2)O(2) was determined by comparing their ability to slow fluorescence generated by a H(2)O(2) 'detector' with that of desferrioxamine solutions. H(2)O(2) was produced by glucose oxidase-catalysed glucose oxidation. The capacity to remove H(2)O(2) was expressed as equivalent concentration of desferrioxamine. The method showed changes in the capacity of H(2)O(2) removal after treatment with ter-butylhydroperoxide or glutathione. The H(2)O(2) removal capacity of homogenates and mitochondria from rat liver, heart, and skeletal muscle was compared with their overall antioxidant capacity. For homogenates, the order of both antioxidant and H(2)O(2) removal capacities was liver>heart>muscle. For mitochondria, the order of the antioxidant capacities mirrored that of the homogenates, while the order of the H(2)O(2) removal capacities was heart>muscle>liver. Because H(2)O(2) removal is not only due to H(2)O(2)-metabolizing enzymes, but also to hemoproteins that convert H(2)O(2) into more reactive radicals via Fenton reaction, the higher concentration of cytochromes in mitochondria of cardiac and skeletal muscles can explain the above discrepancy. A higher H(2)O(2) removal capacity was found to be associated with a higher rate of H(2)O(2) release by mitochondria, indicating that the order of H(2)O(2) release rate mirrors that of H(2)O(2) production rate. We suggest that the different capacities of the mitochondria from the three tissues to produce reactive oxygen species are due to differences in the concentration of respiratory mitochondrial chain components in the reduced form.
Asunto(s)
Citocromos/metabolismo , Peróxido de Hidrógeno/metabolismo , Extractos Hepáticos/metabolismo , Mitocondrias/metabolismo , Animales , Antimicina A/metabolismo , Antioxidantes/química , Antioxidantes/metabolismo , Calibración , Deferoxamina/química , Glutatión/agonistas , Peróxido de Hidrógeno/química , Extractos Hepáticos/química , Masculino , Mitocondrias/química , Músculo Esquelético/metabolismo , Miocardio/metabolismo , Consumo de Oxígeno , Ratas , Ratas Wistar , terc-Butilhidroperóxido/antagonistas & inhibidoresRESUMEN
PURPOSE: to evaluate the activity and toxicity of the combination cisplatin plus vinorelbine plus amifostine in advanced non small cell lung cancer (NSCLC). PATIENTS AND METHODS: a two-stage Simon design was applied. To proceed after the first stage, responses from seven of 19 patients were needed. Overall, 17 responses from 40 treated patients were required to comply with the design parameter. Inclusion criteria were cyto-histologically proven stage IIIB-IV NSCLC; age of 70 years or less; Eastern Cooperative Oncology Group (ECOG) performance status of 2 or less; normal cardiac, hepatic, renal and bone marrow functions; and no previous chemotherapy. Patients were staged by physical examination, biochemistry, chest radiograph, brain, thoracic and abdominal computed tomographic (CT) scans, and bone scan. All patients received cisplatin 100 mg/m(2) intravenously (iv) day 1, vinorelbine 25 mg/m(2) iv days 1-8-15-22, amifostine 740 mg/m(2) iv day 1 every 4 weeks up to six cycles. Eleven of 40 enrolled patients were stage IIIB and 29 stage IV, with a median age of 57 years (range, 38-70 years). RESULTS: all patients were evaluable for response and toxicity (intention to treat analysis). We observed 20 (50%) objective responses, with four (10%) complete responses. Median time to progression was 20 weeks, and median survival was 45 weeks. The toxicity was manageable. The reported main toxicities were neutropenia grade 4 in 10% of patients, grade 1 and grade 3 nephrotoxicity both in 5% of patients and grade 1 amifostine-related hypotension in 15% of patients. CONCLUSION: these data show that cisplatin plus vinorelbine plus amifostine is an active and feaseable regimen in stage IIIB-IV NSCLC. A phase III trial comparing cisplatin plus vinorelbine versus cisplatin plus vinorelbine plus amifostine in advanced NSCLC is warranted.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Neoplasias Pulmonares/tratamiento farmacológico , Adulto , Anciano , Amifostina/administración & dosificación , Amifostina/uso terapéutico , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Carcinoma de Pulmón de Células no Pequeñas/diagnóstico , Carcinoma de Pulmón de Células no Pequeñas/mortalidad , Cisplatino/administración & dosificación , Cisplatino/uso terapéutico , Esquema de Medicación , Femenino , Humanos , Infusiones Intravenosas , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/mortalidad , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Tasa de Supervivencia , Tomografía Computarizada por Rayos X , Resultado del Tratamiento , Vinblastina/administración & dosificación , Vinblastina/uso terapéuticoRESUMEN
We recently reported that hyperthyroidism affects the heart response to ischemia/reperfusion. A significant tachycardia during reperfusion was associated with an increase in the oxidative stress of hearts from T3-treated animals. In the present study we checked the possible role of nitric oxide (NO) in this major stress induced by the hyperthyroid state. We compared the functional recovery from ischemia/reperfusion of Langendorff preparations from euthyroid (E) and hyperthyroid (H, ten daily intraperitoneal injections of T3, 10 microg/100 g body weight) rats, in the presence and in the absence of 0.2 mM Nomega-nitro-L-arginine (L-NNA). At the end of the ischemia/reperfusion protocol (10 min preischemic perfusion, 20 min global ischemia, 30 min reperfusion) lipid peroxidation, antioxidant capacity (CA) and susceptibility to in vitro oxidative stress were determined on heart homogenates. The main effect of hyperthyroidism on the reperfusion functional response was confirmed to be a strong tachycardic response (154% recovery at 25 min reperfusion) accompanied by a low recovery in both left ventricular diastolic pressure (LVDP) and left ventricular dP/dtmax. This functional response was associated with a reduction in CA and an increase in both lipid peroxidation and susceptibility to oxidative stress. Perfusion of hearts with L-NNA per se had small but significant negative chronotropic and positive inotropic effects on preischemic performance of euthyroid rat hearts only. More importantly, L-NNA perfusion completely blocked the reperfusion tachycardic response in the hyperthyroid rats. Concomitantly, myocardium oxidative state (lipid peroxidation, CA and in vitro susceptibility to oxidative stress) of L-NNA perfused hearts was similar to that of E animals. These results suggest that the higher reperfusion-induced injury occurring in hyperthyroid animals is associated with overproduction of nitric oxide.
Asunto(s)
Hipertiroidismo/complicaciones , Daño por Reperfusión Miocárdica/etiología , Óxido Nítrico/fisiología , Animales , Antioxidantes/metabolismo , Inhibidores Enzimáticos/farmacología , Hipertiroidismo/fisiopatología , Inyecciones Intraperitoneales , Peroxidación de Lípido , Masculino , Isquemia Miocárdica , Óxido Nítrico Sintasa/antagonistas & inhibidores , Nitroarginina/farmacología , Estrés Oxidativo , Ratas , Ratas Wistar , Taquicardia/etiología , Triyodotironina/administración & dosificaciónRESUMEN
Hyperthyroidism has been reported to decrease heart antioxidant capacity and increase its susceptibility to in vitro oxidative stress. This may affect the heart response to ischemia-reperfusion, a condition that increases free radical production. We compared the functional recovery from in vitro ischemia-reperfusion (Langendorff) of hearts from euthyroid (E), hyperthyroid (H, ten daily intraperitoneal injections of T3, 10 microg/100g body weight), vitamin E-treated (VE, ten daily intramuscular injections, 20 mg/100g body weight) and hyperthyroid vitamin E-treated (HVE) rats. We also determined lipid peroxidation, tissue antioxidant capacity and the tissue capability to face an oxidative stress in vitro. A significant tachycardia was displayed during reperfusion following 20 min ischemia by the hyperthyroid hearts, together with a low recovery of left ventricular developed pressure (LVDP) and left ventricular dP/dt(max). When H hearts were paced at 300 beats/min, the functional recovery (LVDP and dP/dt(max)) was close to 100% and significantly higher than in E paced hearts. At the end of the ischemia-reperfusion protocol, myocardium antioxidant capacity was significantly lower, whereas lipid peroxidation and the susceptibility to in vitro oxidative stress were higher in the T3 treated (H) than in euthyroid rats. The in vitro tachycardic response, the reduction in the antioxidant capacity and the increase in lipid peroxidation were prevented by treatment of hyperthyroid rats with vitamin E (HVE). These results suggest that the tachycardic response to reperfusion following chronic T3 pretreatment was associated with the reduced capability of the heart to face oxidative stresses in hyperthyroidism.
Asunto(s)
Antioxidantes/farmacología , Corazón/fisiopatología , Hipertiroidismo/fisiopatología , Daño por Reperfusión Miocárdica/fisiopatología , Vitamina E/farmacología , Animales , Antioxidantes/metabolismo , Presión Sanguínea/efectos de los fármacos , Boratos/farmacología , Circulación Coronaria/efectos de los fármacos , Electrocardiografía , Hipertiroidismo/patología , Peroxidación de Lípido/efectos de los fármacos , Masculino , Membranas/patología , Daño por Reperfusión Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/patología , Miocardio/metabolismo , Miocardio/patología , Tamaño de los Órganos/efectos de los fármacos , Estrés Oxidativo/fisiología , Ratas , Ratas Wistar , Vitamina E/metabolismoRESUMEN
In this study, oxygen consumption and H(2)O(2) release rate by succinate or pyruvate/malate supplemented mitochondria isolated from skeletal muscle of trained and untrained rats were investigated. The overall mitochondrial antioxidant capacity and the effect of preincubation of mitochondria with GDP, an inhibitor of uncoupling proteins UCP1 and UCP2, on both succinate-supported H(2)O(2) release and membrane potential were also determined. The results indicate that training does not affect mitochondrial oxygen consumption with both complex-I- and complex II-linked substrates. Succinate-supported H(2)O(2) release was lower in trained than in untrained rats both in State 4 and State 3. Even the antimycin A-stimulated release was lower in trained rats. When pyruvate/malate were used as substrates, H(2)O(2) release rate was lower in trained rats only in the presence of antimycin A. The increase of mitochondrial protein content (determined by the ratio between cytochrome oxidase activities in homogenates and mitochondria) in trained muscle was such that the succinate-supported H(2)O(2) release per g of tissue was not significantly different in trained and untrained rats, while that supported by pyruvate/malate was higher in trained than in untrained animals. The lack of training-induced changes in overall antioxidant capacity of mitochondria indicates that the decrease in mitochondrial H(2)O(2) release cannot be attributed to a greater capacity of mitochondria to scavenge the reactive oxygen intermediates derived from univalent O(2) reduction by respiratory chain components. In contrast, the above decrease seems to depend on the drop induced by training in mitochondrial membrane potential. These training effects are not due to an increased level of mitochondrial uncoupling protein, because in the presence of GDP the increase in both membrane potential and H(2)O(2) release was greater in untrained than in trained rats.
Asunto(s)
Peróxido de Hidrógeno/metabolismo , Mitocondrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Condicionamiento Físico Animal/fisiología , Adenosina Difosfato/farmacología , Animales , Antimicina A/farmacología , Antioxidantes/metabolismo , Complejo IV de Transporte de Electrones/metabolismo , Radicales Libres/metabolismo , Guanosina Difosfato/farmacología , Malatos/metabolismo , Masculino , Potenciales de la Membrana/efectos de los fármacos , Mitocondrias Musculares/efectos de los fármacos , Mitocondrias Musculares/enzimología , Músculo Esquelético/citología , Oxígeno/metabolismo , Resistencia Física/fisiología , Ácido Pirúvico/metabolismo , Ratas , Ratas Wistar , Especies Reactivas de Oxígeno/metabolismo , Rodamina 123/metabolismo , Ácido Succínico/metabolismo , Desacopladores/antagonistas & inhibidores , Desacopladores/metabolismoRESUMEN
The rat heart protection offered by vitamin E against oxidative stress after ischaemia-reperfusion was studied by using a new methodological approach. Functional recovery of hearts from ischaemia-reperfusion was correlated with a traditional index of oxidative stress such as lipid peroxidation and with antioxidant capacity and susceptibility to oxidants of the tissue evaluated by enhanced chemiluminescence techniques. Rats were treated with ten daily i.m. injections of 100 mg/kg body weight of vitamin E. The functional recovery during reperfusion (20 min, following 45 min ischaemia) of Langendorff preparations from control (vehicle-injected) and vitamin E treated rats was evaluated in terms of heart rate, left ventricular developed pressure (LVDP), double product (= heart rate. LVDP) and coronary flow recovery. Vitamin E treatment significantly improved functional recovery of heart rate, LVDP, double product and coronary flow. It also increased the level of vitamin E and reduced the levels of both malondialdehyde and hydroperoxides in the heart tissue at the end of the ischaemia-reperfusion protocol. In contrast, it did not affect the antioxidant capacity and the response of heart homogenates to in vitro oxidative stress measured after ischaemia-reperfusion. These results show a protective action of vitamin E treatment against lipid peroxidation and cardiac dysfunction associated with ischaemia-reperfusion. Although the precise mechanism of this protection is not evident, our model in part suggests a role of vitamin E other than as a free radical scavenger.
Asunto(s)
Antioxidantes/uso terapéutico , Isquemia Miocárdica/tratamiento farmacológico , Daño por Reperfusión Miocárdica/prevención & control , Vitamina E/uso terapéutico , Animales , Circulación Coronaria/efectos de los fármacos , Frecuencia Cardíaca/efectos de los fármacos , Peroxidación de Lípido/efectos de los fármacos , Masculino , Isquemia Miocárdica/metabolismo , Daño por Reperfusión Miocárdica/metabolismo , Estrés Oxidativo/efectos de los fármacos , Ratas , Ratas Wistar , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
Young male rats were sacrificed either at rest or immediately after a single bout of swimming lasting either 5 or 8 h. Mitochondrial population, obtained by centrifugation (10,000g for 10 min) from liver homogenates freed from debris and nuclei, was resolved by differential centrifugation into three fractions. Homogenates and mitochondrial preparations were examined for their protein content, oxidative capacity (by cytochrome oxidase activity), peroxidative processes (by thiobarbituric acid reactive substance and hydroperoxide levels), antioxidant status (by reduced glutathione and vitamin E levels and whole antioxidant capacity), and susceptibility to in vitro oxidative stress. In all groups, the antioxidant level was smaller and oxidative capacity, lipid peroxidation, and susceptibility to oxidants were greater in the heavy mitochondrial fraction. Exercise of shorter duration did not significantly affect most of the parameters; only the resulting homogenate glutathione level and susceptibility to oxidative stress decreased and increased, respectively, compared with control values. In contrast, more prolonged exercise was associated with increased lipid peroxidation and susceptibility to oxidative stress and decreased antioxidant levels in all preparations. The contribution of each fraction to the whole mitochondrial population was also modified in that the heavy fraction decreased and light fractions increased. These results suggest that liver antioxidant defence systems are able to withstand oxidative challenge due to low-intensity exercise of moderate duration. In contrast, the free radical production associated with long-lasting exercise causes oxidative injury in cellular components and in particular induces protein degradation in the heavy mitochondrial fraction characterized by higher susceptibility to oxidative stress.
Asunto(s)
Mitocondrias Hepáticas/metabolismo , Esfuerzo Físico/fisiología , Adenosina Trifosfato/metabolismo , Aerobiosis , Animales , Antioxidantes/metabolismo , Fraccionamiento Celular , Complejo IV de Transporte de Electrones/metabolismo , Radicales Libres/metabolismo , Glutatión/metabolismo , Peroxidación de Lípido , Masculino , Oxidación-Reducción , Estrés Oxidativo , Proteínas/metabolismo , Ratas , Ratas WistarRESUMEN
Whole mitochondrial population and three mitochondrial fractions were resolved by differential centrifugation from liver homogenates from euthyroid, hyperthyroid (ten daily i.p. injections of triiodothyronine (T3), 10 microg/100 g body weight) and hyperthyroid vitamin E-treated (ten daily i.m. vitamin E injections, 20 mg/100 g body weight) rats. Homogenates and mitochondrial preparations were examined for their protein content, oxidative capacity, lipid peroxidation, antioxidant status, and susceptibility to oxidative stress. In all groups, antioxidant level was smaller and oxidative capacity, lipid peroxidation, and susceptibility to oxidants were greater in the heavy mitochondrial fraction. T3 treatment was associated with increased oxidative capacity, lipid peroxidation, and susceptibility to oxidative stress, and decreased antioxidant levels in all preparations. It was also associated with increased mitochondrial protein content of homogenate and altered quantitative presence of the mitochondrial fractions. The vitamin E effects on the T3-induced changes were different for the different parameters. Vitamin E did not modify the mitochondrial protein content in liver and oxidative capacity of the various preparations, reduced the changes in both susceptibility to oxidants and contribution of each fraction to the whole mitochondrial population, and reinstated euthyroid values for antioxidant capacity and lipid peroxidation. The incomplete recovery of euthyroid resistance to oxidants in vitamin E-treated rats is due to the vitamin inability to reinstate the levels of both antioxidants and hemoproteins, on which such a resistance depends. The vitamin E effect on the composition of the mitochondrial population is more difficult to explain, because of the complexity of the mechanisms underlying the mitochondrial population modulation by thyroid hormone. However, available data suggest that such a modulation occurs through changes in the turnover of the mitochondrial fractions to which an induction of mitochondrial protein synthesis and accelerated antioxidant-sensitive degradation contribute in different measure.