Stress-induced desensitization of the cardiovascular response to noradrenaline in unanesthetized rats

The present study was undertaken in order to analyse the effect of swimming stress on the blood pressure response to noradrenaline (NA) in unanesthetized rats. Swimming induced a desensitization of the blood pressure response to NA which was not blocked by previous animal treatment with prazosin (0.1 mg/kg). However, rats submitted to stress showed increased sensitivity to the prazosin blocking effect. The results suggest that swimming-induced desensitization of the cardiovascular response to NA is mediated by alpha rather than beta-1 adrenoceptors.