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ECPB 2013, 62(2): 69–75
Clinical physiology and biochemistry

Changes in the activity of enzymes in the system of antioxidant protection and the state of NADH + Н+-methemoglobin reductase system of hemoglobin in the blood of patients with lung cancer

FEDEVYCH YU.
Abstract

Changes in the activity of enzymes in the system of antioxidant protection and the state of NADH + Í+-methemoglobin reductase system of hemoglobin in the blood of patients with lung cancer were investigated. In the result of investigation it was established that significant changes are observed both before and after the treatment of patients with neoplasms in the lungs. In particular, it was found that in comparison with the control group (donors) a significant increase in the concentration of malonic dialdehyde by 1,48 times was observed in the patients with lung cancer. In the postoperative period it has gradually decreased. Similar alterations are observed in the case of changes in the concentration of the nitrite anion, which it is by 1,68 times bigger in comparison with the control group. Most likely it is connected with the formation of a high reactivity intermediate compound of peroxynitrite.

The changes in the activity of such enzymes as glutathione reductase and glutathione peroxidase have also been established. Thus, the activity of glutathione reductase in the patients increased by 5 times in comparison with the control group. It has gradually decreased in the postoperative period, although even on the 21st day it did not return to norm and exceeded the measure in the control group by 2,22 times. In the preoperative period the activity of glutathione peroxidase in patients decreased by 3,43 times in comparison with the control group. In the postoperative period the activity of this enzyme has gradually increased, but has not reached the control value. The obtained results are indicative of the fact that the system of antioxidant protection, especially its glutathione component, changes its activity, which is most likely connected with the growth of products of lipid peroxygenation.

During the investigation of the state of oxidation-reduction reactions in both donors and patients with lung cancer the changes in the activity of such an important enzyme as erythrocyte NADH + Í+-methemoglobin reductase were researched. This enzyme performs the function of recovering hemoglobin from its met-form. Functional activity of this enzyme accounts for almost 80% of reduced hemoglobin. In the result of the conducted investigation it was observed that the activity of the enzyme decreased by 2,24 times in comparison with the activity in the control group. At a later stage, after the operative intervention, the activity of this enzyme has gradually increased. Therefore, these results indicate that before the operation the activity of NADH + Í+-methemoglobin reductase in the patients decreased, which is obviously attributable to the reduction of NADH +.

At a later stage, in the postoperative period, the level of activity is gradually increasing, which is obviously attributable to the increase in recovered coenzymes. On the whole, decrease in activity of this enzyme can cause the accumulation of methemoglobin, which, in its turn, leads to the development of hypoxia and intoxication.

The obtained results are indicative of the accumulation of products of lipid peroxidation in the blood serum, as well as of the increase of intensity of the processes that lead to their formation, and decrease in activity of antioxidant enzymes and activity of erythrocyte NADH + Í+-methemoglobin reductase, which causes deterioration of oxygenbinding and oxygen-carrying capacities of the system.

In the result of changes in these factors, pathogenetic steady states of nonspecific adaptive compensation are formed, which leads to the decrease in functional capacity of erythrocytes. The obtained results can be used for the purpose of an objective assessment of structural and functional state of oxygen-binding capacities of hemoglobin and erythrocytes in patients under conditions of pathologies accompanied by the development of hypoxic states, destructive diseases, and intoxication.

Keywords: blood, hemoglobin, NADH + Í+-methemoglobinreductase, glutathioneperoxidase, glutathione reductase, lipid peroxidation

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