Comparing the effects of physical and psychological stress on responsiveness of isolated rat aorta

ABSTRACT

Stress, particularly when chronic, has many adverse effects on human health. The role of stress has been elucidated in cardiovascular disorders such as hypertension, myocardial infraction, atherosclerosis, myocardial ischemia, and cardiac arrhythmia. The aim of this study is to determine and compare the effect of chronic physical and psychological stress on the contractility of isolated rat aorta. Male albino Wistar rats weighing 200-250 g were used. Three groups of rats, the physical stress, psychological stress and the control qroups [n = 12 each] were used in this study. Physical and psychological stress were induced using the communication box for three weeks. At the end of the stress period animals were anesthetized, following which the abdomen was opened and the thoracic aorta dissected and endothelium denuded. The aorta ring were connected to isometric transducer and contractions in response to 5- 60 mM potassium chloride and 10-10-10-6 phenylephrine were measured. Serum corticosterone was measured by radioimmunoassay before and after intervention in all groups. In the physical stress group serum corticosterone levels rose from 402 +/- 40 to 721 +/- 94 ng/ml after stress [p < 0.05]. This value in the psychological stress group reached 946 +/- 84 ng/mL from the initial value of 400 +/- 114 ng/mL [p < 0.05]. Aorta responses to potassium chloride and phenylephrine were significantly lower compared to the control group [p < 0.05] in both the stress groups. The results of this study indicate that chronic physical and psychological stress cause an increase in serum corticosterone and decrease aorta responsiveness in isolated rat aorta, implying that psychological stress has detrimental effects on the vascular system similar to those of physical stress