Mechanical stimulation of baroreceptors lowered pain threshold in normotensives but increased tolerance to intense electric stimulation in borderline hypertensives.
Does mechanical stimulation of baroreceptors alter pain threshold and electrical brain activity in normotensive and borderline hypertensive humans?
The effect of baroreceptor stimulation on pain sensation depends on tonic blood pressure, supporting the hypothesis that operantly-conditioned blood pressure elevation under stress may be specific to individuals predisposed to essential hypertension.
ABSTRACT It has been hypothesized that activation of the baroreceptor reflex arc, by its central nervous inhibitory effects, is involved in an operant learning mechanism of blood pressure elevation. The present study investigated the effects of mechanical stimulation of the baroreceptors in the carotid sinus on pain threshold and electrical brain activity in two groups of humans with different tonic blood pressure levels. In normotensives, baroreceptor stimulation lowered pain threshold as compared to a control condition, while borderline hypertensives tolerated more intense electric stimulation when baroreceptors were activated. A marked reduction of the contingent negative variation in anticipation of the aversive stimulation accompanied baroreceptor stimulation, probably a consequence of baroreceptor afferent impulses exerted via brainstem centers to cerebral cortex. The distribution of the potential change across the scalp depended on the tonic blood pressure, indicating differences in brain functioning between normotensives and borderline hypertensives. The present results suggest that the hypothesis of an operantly‐conditioned blood pressure elevation under stress may be valid only in subjects with a predisposition for essential hypertension.
Elbert et al. (Fri,) conducted a other in Normotension and borderline hypertension. Mechanical stimulation of the baroreceptors in the carotid sinus vs. Control condition was evaluated on Pain threshold and electrical brain activity (contingent negative variation). Mechanical stimulation of baroreceptors lowered pain threshold in normotensives but increased tolerance to intense electric stimulation in borderline hypertensives.