Adrenergic and pressure-induced modulation of carotid sinus baroreceptors in rabbit.
The sympathetic control of the carotid sinus baroreceptor activity was studied in rabbits. Stimulation of the cervical sympathetic trunk (10 Hz, 1 ms, 4-12 V) elicited an increase in discharge frequency of the non-medullated baroreceptor afferents but not of the medullated fibers. An isolated carotid sinus area preparation was used to examine the influence of noradrenaline perfusion on baroreceptor activity. Non-medullated baroreceptor afferents, but not the medullated afferents, responded to noradrenaline perfusion (10(-6) g/ml) with a significant increase in firing rate. Short-term resetting of the baroreceptors was also studied with the same preparation. After perfusing the sinus at a hypertensive level for 30 min the pressure-response curves of both the non-medullated and the medullated baroreceptor afferents shifted to the right with increased thresholds and decreased maximal discharge frequencies. The extent of the short-term resetting was greater in non-medullated afferents than in medullated ones. It is concluded that the carotid sinus baroreceptors with non-medullated afferents are under the sympathetic control. The physiological significance of this is discussed.
D000818:Animals; D002346:Carotid Sinus / Q000294:innervation*; D004558:Electric Stimulation; D005260:Female; D008297:Male; D009431:Neural Conduction; D009638:Norepinephrine / Q000494:pharmacology*; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D011312:Pressure; D011817:Rabbits
D009638:Norepinephrine