Baroreceptor activation reduces reactivity to noxious stimulation: implications for hypertension.

The hypothesis was tested that an acute rise of blood pressure may reduce reactivity to noxious stimuli through a baroreceptor-mediated reduction of cerebral arousal. When blood pressure was raised by an infusion of phenylephrine, rats showed less running to terminate or avoid noxious stimuli than during saline infusions. This effect was not seen in rats with denervated baroreceptors. The results suggest that a rise of blood pressure could have motivational consequences significant for human hypertension.