Activation of carotid baroreceptors inhibits spinal reflexes in man

Abstract

SummaryThe present study was designed to investigate the effect of baroreceptors on a spinal reflex. The Achilles tendon reflex ( reflex), a monosynaptic spinal reflex, was chosen as an indicator of descending influences of central activation.The baroreceptors are stretch receptors which respond to extensions of the arterial wall. Carotid sinus baroreceptors can be manipulate non-invasively by means of a cuff around the neck. In this study, the phase-related external suction (PRES) neck cuff technique was used. PRE applies short changes in cuff pressure as a function of heart cycle phase, controlling for non-specific effects fomid in other barorecepto manipulation methods.The T reflex was reduced when elicited during the highest levels of baroreceptor activation. Reflex amplitude was largest when elicited durin the lowest levels of baroreceptor activation. These results are consistent with previous findings that baroreceptor activation reduces eNS excitability.

Psychophysiology of arterial baroreceptors and the etiology of hypertension

“…4). In the Rau et al (1993a) study, baroreceptor stimulation clearly suppressed the Achilles tendon reflex in each of the 12 subjects.…”

“…The reflex is elicited at time zero. The EMG from m. soleus is averaged across 32 trials per condition and displayed here for one subject (data from Rau et al, 1993a).…”

“…We chose the Achilles tendon reflex (T-reflex) as an indicator of descending modulatory effects of baroreceptor activation (Rau et al, 1993a). The T-reflex was evoked by a tendon tap, stretching the calf muscles.…”

Arterial baroreflex modulation influences postural sway

“…Previous studies using NS reported that artificially increased baroreceptor activation is associated with inhibition of the stretch reflex [9,22], suggesting a relationship between these structures, possibly through modulation of reticular formation neurons by the baroreceptor integration nucleus [22]. The baroreceptor modulation of sway signal that we showed in the present study could be one aspect of the interaction between structures controlling posture and those involved with cardiovascular system regulation.…”

Sitting position does not alter minimum alveolar concentration for desflurane

“…2,3 Conversely, the sitting position and head-up tilt, which result in baroreceptor unloading, produce an electroencephalogram-determined arousal 4,5 and decrease current perception threshold. 6 In animals, the use of vasopressors did not affect minimum alveolar concentration (MAC) of halothane for immobility, 7 whereas sympathoexcitation, a physiological consequence of baroreceptor unloading, increased MAC for cyclopropane and halothane.…”