RESUMEN
OBJECTIVE: Ions, particularly calcium ions, play an important role in ischemia-reperfusion cell injury. In this study, we investigated the action of verapamil on the mitochondrial function of kidneys submitted to ischemia without blood reperfusion in order to study isolated early and late ischemic effects. MATERIALS AND METHODS: 44 rats were submitted to bilateral warm renal ischemia for 30 minutes. The kidneys were then immediately reperfused with saline or Euro-Collins (EC) solution, with and without previous administration of 0.35 mg/kg of verapamil. Mitochondrial function was assessed at the end of renal perfusion and after 24 hours of cold preservation. RESULTS: In kidneys perfused with saline, verapamil allowed a significant early preservation of state III mitochondrial respiration, a result that was no longer evident after 24 hours. In kidneys perfused with EC solution, verapamil did not change state III for either early or late evaluations. Comparison of the groups showed that the results obtained for kidneys perfused with EC were always superior to those obtained for the saline group, except for the initial analysis of kidneys treated with saline and verapamil, which showed results similar to those obtained with EC perfusion alone. CONCLUSION: Administration of verapamil before warm ischemia provides partial and short-lasting functional protection of the mitochondrial function in kidneys perfused with sodium rich saline. With Euro-Collins solution, verapamil did not show any additional beneficial effect. This fact permits us to conclude that protective action is effective only under conditions that facilitate increased sodium uptake and/or potassium loss.
Asunto(s)
Bloqueadores de los Canales de Calcio/farmacología , Soluciones Hipertónicas/farmacología , Riñón/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Verapamilo/farmacología , Isquemia Tibia/métodos , Animales , Isquemia Fría/métodos , Riñón/citología , Masculino , Mitocondrias/fisiología , Perfusión , Ratas , Ratas WistarRESUMEN
OBJECTIVE: Ions, particularly calcium ions, play an important role in ischemia-reperfusion cell injury. In this study, we investigated the action of verapamil on the mitochondrial function of kidneys submitted to ischemia without blood reperfusion in order to study isolated early and late ischemic effects. MATERIALS AND METHODS: 44 rats were submitted to bilateral warm renal ischemia for 30 minutes. The kidneys were then immediately reperfused with saline or Euro-Collins (EC) solution, with and without previous administration of 0.35 mg/kg of verapamil. Mitochondrial function was assessed at the end of renal perfusion and after 24 hours of cold preservation. RESULTS: In kidneys perfused with saline, verapamil allowed a significant early preservation of state III mitochondrial respiration, a result that was no longer evident after 24 hours. In kidneys perfused with EC solution, verapamil did not change state III for either early or late evaluations. Comparison of the groups showed that the results obtained for kidneys perfused with EC were always superior to those obtained for the saline group, except for the initial analysis of kidneys treated with saline and verapamil, which showed results similar to those obtained with EC perfusion alone. CONCLUSION: Administration of verapamil before warm ischemia provides partial and short-lasting functional protection of the mitochondrial function in kidneys perfused with sodium rich saline. With Euro-Collins solution, verapamil did not show any additional beneficial effect. This fact permits us to conclude that protective action is effective only under conditions that facilitate increased sodium uptake and/or potassium loss.
Asunto(s)
Ratas , Animales , Masculino , Bloqueadores de los Canales de Calcio/farmacología , Soluciones Hipertónicas/farmacología , Riñón/citología , Mitocondrias/fisiología , Verapamilo/farmacología , Isquemia/etiología , Riñón/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Perfusión , Ratas WistarRESUMEN
BACKGROUND: The role of mitochondrial lesions in the pathogenesis of irreversible cellular ischemia is controversial. The inability to restore mitochondrial function is correlated with the inability to reverse cell damage in various tissues. The objective of the present study was to compare parameters associated with oxidative phosphorylation and the inner mitochondrial membrane potential of skeletal muscle of rats submitted to total ischemia in order to determine which mitochondrial alterations are mainly affected in this condition. MATERIAL AND METHODS: Wistar rats were submitted to 5 h total ischemia using the tourniquet method (ischemic limb group). The contralateral limb of each rat was used as control (control limb group). After the ischemic period, muscle biopsies were obtained for the isolation of the mitochondrial fractions, which were submitted to polarographic analysis for the determination of ADP-activated oxygen consumption (state 3), basal respiration (state 4), and the ratio of the two respiratory activities: the respiratory control ratio (RCR). The potential of the inner mitochondrial membrane was determined by measuring the fluorescence difference between coupled and uncoupled mitochondria using safranine O as indicator. RESULTS: After 5 h of ischemia, a significant reduction of all parameters studied was observed in skeletal muscle submitted to ischemia compared to the control limbs. CONCLUSIONS: Five-hour total ischemia applied to rat skeletal muscle led to the inhibition of the mitochondrial respiratory chain (represented by decreased state 3 and state 4 respiration rates). The percentage decrease in the electrical potential of the inner membrane was similar to the percentage reductions observed for state 4 respiration and the RCR. The parameter mostly affected by ischemia was ADP-activated respiration (state 3).
Asunto(s)
Isquemia/fisiopatología , Mitocondrias Musculares/fisiología , Músculo Esquelético/irrigación sanguínea , Adenosina Difosfato/farmacología , Animales , Miembro Posterior , Masculino , Potenciales de la Membrana , Consumo de Oxígeno/efectos de los fármacos , RatasRESUMEN
Neste trabalho, a comparaçao da reserva de glicogênio é utilizada para entender as modificaçoes na sensibilidade mitocondrial ao íon cálcio. Basicamente porque alteraçoes mitocondriais que envolvam perda da atividade de fosforilaçao oxidativa provocam rápida utilizaçao dos estoques de glicogênio. Nossos resultados sugerem que as alteraçoes mitocondriais fazem parte do mecanismo de lesao isquêmica.