TY - JOUR
T1 - Does pulsatile and sustained neck pressure or neck suction produce differential cardiovascular and sympathetic responses in humans?
AU - Ogoh, Shigehiko
AU - Fadel, Paul J.
AU - Hardisty, Janelle M.
AU - Wasmund, Wendy L.
AU - Keller, David M.
AU - Raven, Peter B.
AU - Smith, Michael S.
PY - 2003/9
Y1 - 2003/9
N2 - Although square-wave sustained and R wave-triggered pulsatile stimuli have been used to assess carotid baroreflex (CBR) function in humans, it remains unclear whether these different stimulus protocols elicit comparable responses and whether CBR responses adapt during prolonged stimulation. Thus, we measured muscle sympathetic nerve activity (MSNA), heart rate (HR) and mean arterial pressure (MAP) in response to +30 Torr neck pressure (NP) and -30 Torr neck suction (NS) delivered for 20 s either as a sustained or pulsatile stimulus. CBR-mediated changes in MSNA, HR and MAP were similar with sustained and pulsatile stimuli. The time course of MSNA and HR responses identified that significant changes occurred during the initial 5 s and were better maintained over 20 s with NP than with NS. Changes in MAP exhibited a slower onset with the peak increase during NP occurring at 10 s (sustained, 7 ± 1 mmHg; pulsatile, 7 ± 1 mmHg; P > 0.05 and the nadir during NS occurring at 20 s (sustained, -7 ± 1 mmHg; pulsatile, -9 ± 2 mmHg, P > 0.05). These data demonstrate that sustained and pulsatile NP and NS produce comparable CBR-mediated responses. Furthermore, despite MSNA and HR returning towards baseline during NS, CBR-mediated changes in MAP are well maintained over 20 s of NS and NP.
AB - Although square-wave sustained and R wave-triggered pulsatile stimuli have been used to assess carotid baroreflex (CBR) function in humans, it remains unclear whether these different stimulus protocols elicit comparable responses and whether CBR responses adapt during prolonged stimulation. Thus, we measured muscle sympathetic nerve activity (MSNA), heart rate (HR) and mean arterial pressure (MAP) in response to +30 Torr neck pressure (NP) and -30 Torr neck suction (NS) delivered for 20 s either as a sustained or pulsatile stimulus. CBR-mediated changes in MSNA, HR and MAP were similar with sustained and pulsatile stimuli. The time course of MSNA and HR responses identified that significant changes occurred during the initial 5 s and were better maintained over 20 s with NP than with NS. Changes in MAP exhibited a slower onset with the peak increase during NP occurring at 10 s (sustained, 7 ± 1 mmHg; pulsatile, 7 ± 1 mmHg; P > 0.05 and the nadir during NS occurring at 20 s (sustained, -7 ± 1 mmHg; pulsatile, -9 ± 2 mmHg, P > 0.05). These data demonstrate that sustained and pulsatile NP and NS produce comparable CBR-mediated responses. Furthermore, despite MSNA and HR returning towards baseline during NS, CBR-mediated changes in MAP are well maintained over 20 s of NS and NP.
UR - http://www.scopus.com/inward/record.url?scp=0141634158&partnerID=8YFLogxK
U2 - 10.1113/eph8802586
DO - 10.1113/eph8802586
M3 - Article
C2 - 12955159
AN - SCOPUS:0141634158
SN - 0958-0670
VL - 88
SP - 595
EP - 601
JO - Experimental Physiology
JF - Experimental Physiology
IS - 5
ER -