Evaluation of heart electrical and hemodynamic changes due to hyperkalmia in exercise with administration of propranolol

Abstract

Objectives: Physical exercises induce many biochemical changes including hyperkalmia and increasing of catecholamines in blood circulation. The purpose of this study is to investigate the heart electrical changes induced by hyperkalmia occurring during exercise and also study the protective effects of catecholamines against hyperkalmia. Methods: 12 healthy male volunteers (23 - 19 years) were selected for this study. Each individual performed an exercise using Ergometer to complete exhaustion (increasing 20 watts workload every two minutes) twice, with one week interval. In the first instance they took a placebo, in the second instance, they took 80 mg propranolol, one and half hours before starting the exercise. Before the exercise and in the last 20 seconds of each increment in the workload, electrocardiogram was recorded in all the 12 leads. Results: With each increment in workload heart rate and plasma potassium was increased in both protocols. In protocol of propranolol administration increase in HR was less than of placebo and enhancement of potassium was more. Comparison of two protocols together in ECG changes showed no significant differences. Conclusion: Increase in potassium levels in muscles during exercise can not have toxic effects on heart. Probably catecholamines do not have a main role in defense against hyperkalmia due to exercise. As a result we suggest administration of propranolol can not be limiting factor for the individual physical exercise.