Key result
Unilateral carotid-cardiac reflex responses show similar gains but exhibit inhibitory interaction during bilateral stimulation.
Why the study?
The individual contributions of the right and left carotid sinus baroreflex control of cardiac interval and their interaction during bilateral stimulation were not well characterized in humans.
Do right and left carotid sinus baroreflexes contribute equally to cardiac interval control, and how do they interact bilaterally in healthy men?
Do right and left carotid sinus baroreflexes contribute equally to cardiac interval control, and how do they interact bilaterally in healthy men?
Right and left carotid-cardiac reflex responses are quantitatively similar in humans but exhibit an inhibitory interaction during bilateral stimulation at rest.
Unilateral neck stimulation isolates side-specific baroreflex gains in healthy men; extends physiological mapping but leaves open clinical translation.
To determine the individual contributions of the right and left carotid sinus baroreflex control of the cardiac interval, we measured heart rate [as expressed by R-R interval (RRI)] and mean arterial pressure (MAP) responses elicited by pulsed trains of neck suction or pressure in 20 healthy men. Pulses were delivered using a customized neck collar device partitioned to allow for stimulation of only one side of the neck. Maximal cardiac gains for right, left, and bilateral baroreflexes were determined from the logistic function of RRI responses to changes in estimated carotid sinus pressure (ECSP). Maximal gains for right (5.44 +/- 1.33 ms/Torr ECSP) and left (4.22 +/- 1.44 ms/Torr ECSP, P > 0.05) carotid-cardiac responses did not differ. However, the bilateral gain (6.89 +/- 1.80 ms/Torr ECSP) was less than the simple sum of the right and left gains (9.67 +/- 2.20 ms/Torr ECSP, P < 0.01). We suggest that the right and left carotid-cardiac reflex responses are quantitatively similar in humans and exhibit an inhibitory interaction when compared with the bilateral response under conditions of supine rest in normotensive subjects.
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Williamson et al. (1993) studied Healthy (n=20). Unilateral and bilateral neck suction or pressure vs. Right vs left vs bilateral stimulation was evaluated on Maximal cardiac gains for right and left carotid-cardiac responses (p=>0.05). Right and left carotid-cardiac reflex responses were quantitatively similar (5.44 vs 4.22 ms/Torr, P>0.05) but exhibited an inhibitory interaction during bilateral stimulation (P<0.01).
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