Mitochondrial dysfunction and oxidative stress participate in the development of diabetic complications, however, the mechanisms of their origin are not entirely clear. Coenzyme Q has an important function in mitochondrial bioenergetics and is also a powerful antioxidant. Coenzyme Q (CoQ) regenerates alpha-tocopherol to its active form and prevents atherogenesis by protecting low-density lipoproteins against oxidation. The aim of this study was to ascertain whether the experimentally induced diabetes mellitus is associated with changes in the content of endogenous antioxidants (alpha-tocopherol, coenzymes Q9 and Q10) and in the intensity of lipoperoxidation. These biochemical parameters were investigated in the blood and in the isolated heart and liver mitochondria. Diabetes was induced in male Wistar rats by a single intravenous injection of streptozotocin (45 mg.kg-1), insulin was administered once a day for 8 weeks (6 U.kg-1). The concentrations of glucose, cholesterol, alpha-tocopherol and CoQ homologues in the blood of the diabetic rats were increased. The CoQ9/cholesterol ratio was reduced. In heart and liver mitochondria of the diabetic rats we found an increased concentration of alpha-tocopherol, however, the concentrations of CoQ9 and CoQ10 were decreased. The formation of malondialdehyde was enhanced in the plasma and heart mitochondria. The results have demonstrated that experimental diabetes is associated with increased lipoperoxidation, in spite of the increased blood concentrations of antioxidants alpha-tocopherol and CoQ. These changes may be associated with disturbances of lipid metabolism in diabetic rats. An important finding is that heart and liver mitochondria from the diabetic rats contain less CoQ9 and CoQ10 in comparison with the controls. We suppose that the deficit of coenzyme Q can participate in disturbances of mitochondrial energy metabolism of diabetic animals., J. Kucharská, Z. Braunová, O. Uličná, L. Zlatoš, A. Gvozdjáková., and Obsahuje bibliografii
Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, are effective drugs in the treatment of hypercholesterolemia, however, their undesirable actions are not fully known. We investigated the effects of atorvastatin on the oxidative phosphorylation and membrane fluidity in liver mitochondria, and also on the coenzyme Q (CoQ) content in the mitochondria, liver tissue, and plasma of rats on a standard (C) and hypercholesterolemic (HCh) diet. Atorvastatin was administered at either low (10 mg⋅kg-1) or high dose (80 mg⋅kg-1) for four weeks. The high dose of the drug decreased the concentrations of total cholesterol and triacylglycerols in the plasma and liver of rats on a HCh diet. Administration of atorvastatin was associated with decreased oxygen uptake (state 3), and oxidative phosphorylation rate in the mitochondria of both C and HCh rats. Further, the drug influenced mitochondrial membrane fluidity and dose-dependently reduced concentrations of oxidized and reduced forms of CoQ in the mitochondria. Our findings point to an association between in vivo administration of atorvastatin and impaired bioenergetics in the liver mitochondria of rats, regardless of diet, in conjunction with simultaneous depletion of oxidized and reduced CoQ forms from the mitochondria. This fact may play a significant role in the development of statin-induced hepatopathy., O. Uličná ...[et al.]., and Obsahuje seznam literatury