The influence of exercise-induced oxidative stress on binding and degradation of 125I-insulin by the receptors on erythrocytes.

In the present work we investigated the influence of oxidative stress induced by strenuous exercise on the affinity of a specific insulin receptors on human erythrocytes. 13 male members of the national basketball staff performed a maximal treadmill exercise test. In the blood samples collected before and directly after the test acid-base equilibrium parameters, lactic acid concentrations, glucose and insulin serum levels as well as 125I-insulin binding and degradation by receptor on erythrocytes were measured. As markers of oxidative stress, plasma thiobarbituric acid-reactive substance levels (TBARS) and red blood cells glutathione content (GSH) were determined. After the exercise test TBARS levels increased significantly and GSH concentrations decreased indicating that oxidative stress occurred. Binding of 125I-insulin to the receptors on erythrocytes decreased significantly during the test, while there was only insignificant reduction in 125I-insulin degradation. Correlation analysis and multiple linear regression revealed that changes in insulin degradation by receptors on erythrocytes during exhaustive exercise are determined by oxidative stress, probably via oxidation of sulfhydryl groups of certain enzymes. The affinity of receptors for insulin seems to depend mainly on glucose concentrations.

The influence of oral glucose intake on binding and degradation of 125I-insulin by receptors on erythrocytes as well as on insulin and C-peptide serum levels in patients after myocardial infarction and healthy individuals.

In this study, we investigated the influence of glucose administration on binding and degradation of 125I-insulin by receptors on erythrocytes as well as on insulin and C-peptide serum levels in 15 patients after myocardial infarction and in 15 age-matched healthy persons. Venous blood samples were taken directly before and at 30, 60 and 120 minutes after oral administration of 75 g of glucose. In the collected blood samples serum glucose, insulin and C-peptide levels were determined. Binding and degradation of 125I-insulin by specific receptors on red blood cells were evaluated using the method described by Gambhir and modified by the authors. Serum insulin and C-peptide levels were significantly higher while binding of 125I-insulin to erythrocytes was decreased in patients after myocardial infarction. These results seem to support the hypothesis that insulin resistance and hyperinsulinism play a role in the pathogenesis of ischaemic heart disease. Impaired degradation of 125I-insulin during the oral glucose tolerance test in the patients after myocardial infarction indicates that insulin resistance is located at the receptor level.

[Complex evaluation of body reaction in obese boys boys with systematic physical exertion and a low energy diet]. / Kompleksowa ocena reakcji organizmu otylych chlopców na systematyczny wysilek fizyczny skojarzony z dieta niskoenergetyczna.

This paper presents the results of researched influence of systematic physical effort together with a calorie restricted diet on fourteen-year-old obese boys. We evaluated their physical efficiency (VO2max), body consistency, blood lipid profile the level of non-enzymatic glycosylation of protein, insulinemia, and insulin resistance measured by the binding of 125I-Insulin to erythrocyte receptors. For 21 days, subjects performed 30 minutes of physical effort on a bicycle ergometer with load of 1 W/kg of body mass. Simultaneously, they were subjected to a calorie restricted diet at an average level of 1300 kcal. Before administering of the therapy and following its completion, the maximal amount of oxygen intake and body consistency was determined. Following that, the boy subjects performed an effort on the bicycle ergometer having an intensity of 70% VO2max and, simultaneously, capillary and venous blood was drawn for testing. In the capillary blood samples indices of acid-base balance, the lactate level, and glucose level were determined. In the venous blood samples levels of lipids, immunoreactive insulin, C-peptide and fructosamine were determined. Binding of 125I-Insulin was determined according to the method described by Gambhir and modified by us. Obtained results show that the administered therapy contributed to an increased physical efficiency, a decrease in the body's fatty mass, a reduction by 20% of insulinemia (p < 0.01) and insulin resistance as measured by the amount of 125I-Insulin binding.