Beneficial effect of short-term endurance training on glucose metabolism during rehabilitation after coronary bypass surgery.

AIMS: Our study was aimed at determining whether beneficial modification of carbohydrate metabolism can be obtained after a short-term training program and whether it is associated with an increase in binding and degradation of (125)I-insulin by erythrocyte receptors that suggests a decrease in insulin resistance. METHODS: The study was conducted in a group of 20 patients aged 56 +/- 1.9 years (mean +/- SEM), within 1 to 6 months after coronary bypass surgery. All patients completed 15 training sessions based on 30 min of cycling with a constant load. Before and after a 3-week training program, glucose, insulin, and C-peptide blood levels, as well as binding and degradation of (125)I-insulin by erythrocyte receptors, were determined. RESULTS: A statistically significant decrease was found in the blood glucose level, from 111.2 +/- 4.2 to 97.8 +/- 3.5 mg/dL (p < 0.01); this decrease was not accompanied by significant insulin concentration changes. There was also a significant increase in insulin binding, from 0.535 +/- 0.059 to 0.668 +/- 0.042 pg (125)I/10(11) RBCs (p < 0.01), and degradation from 7.64 +/- 0.54 to 9.49 +/- 0.58 pg (125)I/10(11) RBCs (p < 0.05). CONCLUSION: The results indicated that even short-term endurance training in patients rehabilitated after coronary bypass surgery induced favorable modification of glucose metabolism, presumably caused by a decrease in insulin resistance.

The influence of short-term endurance training on the insulin blood level, binding, and degradation of 125I-insulin by erythrocyte receptors in patients after myocardial infarction.

PURPOSE: This study was directed toward establishing whether and to what extent, short-term endurance training influences the insulin blood level, and the binding and degradation of 125I-insulin by erythrocyte receptors in patients undergoing rehabilitation after myocardial infarction. METHODS: The study was conducted in a group of 60 patients who had had myocardial infarction within the past 1.5 to 3 months and who did not have arterial hypertension and diabetes mellitus. All the patients took a symptom-limited cardiopulmonary exercise test. Before and after the test, venous blood was collected to determine lactic acid and insulin blood levels as well as the binding and degradation of 125I-insulin. The study group was randomized into two subgroups. One subgroup entered into a 3-week in-patient rehabilitation course. The control group was discharged from the hospital and was given no recommendations for physical exercise. The same investigation was repeated 3 weeks later. RESULTS: In the patients (50%) with hyperinsulinemia (insulin resistance index, > 10 microIU/mL), which was detected during the first investigation, insulin blood level decreased from 23.9 +/- 4.4 to 15.0 +/- 1.9 microIU/mL (P < 0.05) after rehabilitation, whereas insulin binding increased from 0.67 +/- 0.05 to 0.85 +/- 0.08 pg 125I/10(11) erythrocytes (P < 0.05). In the control group, which included normal subjects and those with hyperinsulinemia, the results obtained during the first and second investigations showed no statistically significant changes when compared. CONCLUSIONS: The results suggest that a 3-week endurance training period during rehabilitation after myocardial infarction reduces insulin resistance in patients with hyperinsulinemia.

Exercise-induced increase in hydrogen peroxide plasma levels is diminished by endurance training after myocardial infarction.

We have investigated the influence of physical training on exercise-induced changes in free radical activity in patients after myocardial infarction. Seventeen patients admitted to the cardiac rehabilitation center performed a bicycle ergometry before and after a 3-week endurance training program. The oxygen consumption and carbon dioxide production were measured and the ECG and the systemic blood pressure were monitored during the tests. Blood samples for acid-base equilibrium, lactic acid levels and hydrogen peroxide concentrations were collected directly before and after each exercise test. Exercise-induced increases in systolic blood pressure, heart rate and rate-pressure product as well as lactic acid concentrations were significantly less marked during the bicycle ergometry performed after the rehabilitation program. During the initial exercise test hydrogen peroxide levels increased significantly from 7.15+/-0.74 micromol/l before to 9.09+/-1.04 micromol/l 3 min after the test (P=0.0229). In contrast, no significant changes in hydrogen peroxide concentrations were observed during the exercise test performed after the training (6.31+/-1.05 micromol/l before the test, 5.85+/-1.08 micromol/l after the test, P=0.201). These observations suggest that physical training may have a beneficial influence on free radicals' generation in patients after myocardial infarction.

Glucosamine levels in people with ischaemic heart disease with and without type II diabetes.

Glucosamine has a major influence on the impairment of some metabolic mechanisms in the human body. As shown in vitro experiments, it takes part in inducing mechanisms of insulin resistance. Therefore, the purpose of our study was to evaluate glucosamine levels in the serum of patients who suffered myocardial infarction (MI) and who either had or didn't have diagnosed type II diabetes in relation to healthy people. The levels of glucosamine, immunoreactive insulin, C-peptide, glucose and lipid indexes were measured in venous blood in investigated patients. In patients with MI without diabetes the highest concentrations of glucosamine, insulin and C-peptide were noted as compared to the results obtained from other groups of patients. In patients with diabetes, on the other hand, the highest glucose levels were noted as compared to the results of other patients. There were no statistically differences of lipid indexes between two groups of patients following MI. A negative correlation between glucosamine levels and glucose concentrations in patients without diabetes may suggest that glucose does not directly determine glucosamine levels. The returning of insulin levels to normal in patients with hyperinsulinemia (antidiabetic drugs) may play a role in the lowering of glucosamine induced peripheral insulin resistance.

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.