Diabetes mellitus is endocrine disease which is rapidly spreading. According to WHO data for 2013 year, there are nearly 370 million people with diabetes all over the world, and more than 1 million – in Ukraine. But the real sickness rate is much higher.

Development of diabetes mellitus is accompanied with impairment of many organism functions, particularly of the system of energy supply in different tissues. Mitochondria are the basic ″energy stations″ of the cell, where synthesis of ATP upon oxygen presence takes place. The mitochondrial enzymatic systems as well are the source of reactive oxygen species, overgeneration of which leads to intensification of lipids peroxidation and to cell injury. Hyperglycemia is accompanied with growth in glucose autoxidation velocity, that causes the changes in processes of oxygen consumption and energy supply of the cell; intensification of lipids peroxidation and impairment of antioxidant system activity. In spite of the great amount of works about this problem, there is no strict answer, concerning peculiarities of these processes course upon diabetes.

Thus, the aim of our investigation was to estimate oxygen-dependent processes in rat liver upon induced diabetes.

The experiments were carried out using underbred rat males (180–220 g). Animals were divided into control and experimental groups. The experimental rats were injected with streptozotocin intraperitoneally (50 mg/kg) and physiological solution (1 ml) was injected to the control animals. The development of diabetes was estimated by blood glucose concentration. The hepatocytes were isolated by two-staged Seglen method and permeabilized with digitonin (50 μg/million cells). The respiration rate of isolated liver cells was estimated by polarographic method upon succinate (5 mM) oxidation. The malondialdehyde content and the superoxide dismutase, catalase and succinate dehydrogenase activities were determined in liver homogenate. Enzymatic activities were calculated into protein unit, the content of which was estimated by Lowry method. The statistical data analysis was carried out by Student’s criteria with the use of Microsoft Office Excel package. There are impairments of mitochondrial respiratory chain functioning upon diabetes.

Analyzing the system of rats liver energy supply upon induced diabetes we received the data showing no changes in respiration rate in isolated hepatocytes after 14 days of illness. There was tendency to lowering of respiration rate in experimental animals’ intact cells, but these alterations turned out to be not trustworthy. As well as the differences between the control and experimental groups in oxygen consumption velocities upon succinate, ADP and DNP oxidation indices were not reliable. But significant decrease of succinate dehydrogenase activity upon diabetes was established. The intensity of lipids peroxidation in liver has been magnified in 14 days after diabetes inducing.

Since the rate of lipids peroxidation processes is controlled by the system of antioxidant protection, we have investigated the superoxide dismutase and catalase activities. The data concerning the modifications of the antioxidant protection system upon diabetes are ambiguous. Our researches showed the superoxide dismutase and catalase activities increase in experimental rats’ liver in comparison to the control.

Thus, we revealed lowering of succinate dehydrogenase activity in 14 days after diabetes induction, but it does not cause impairments of energy supply in hepatocytes. That is the liver that is able to maintain the normal energy state at early stages of diabetes affects. However, the increase of malondialdehyde level is not compensated by the activation of antioxidant protection system.

Ключові слова: diabetes mellitus, hepatocytes, cell respiration, lipids peroxidation, antioxidants

Повний текст: PDF (Ukr)

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