Influence of different types of stress on selected cardiovascular parameters in rats

Wistar strain male albino rats were exposed to different types of stressors like isolation, immobilization, overcrowding and forced swimming, for a duration of one day, 7 days, 15 days and 30 days and the effect on heart weight, adrenal weight, heart rate, P-R interval and serum transaminase levels were studied. There was a significant increase in the heart weight and adrenal weight in most of the stress subgroups. Tachycardia was seen in all the types of stress upto 7 days, except in the case of overcrowding stress. Serum transaminase level increased significantly in all the types of stress. Among the different types of stress, immobilization and forced swimming had greater effect on the heart weight and heart rate. Increase in the heart rate and heart weight was observed only in the initial period of exposure to a stressor and when the animals were exposed to a prolonged stressor like 15 days and 30 days, there was no further increase in the heart weight and heart rate which may be due to the adaptation of the animal to a chronic stressor.