TY - JOUR
T1 - Responses of muscle sympathetic nerve activity to lower body positive pressure
AU - Fu, Qi
AU - Sugiyama, Yoshiki
AU - Atsunori Kamiya, A.
AU - Shamsuzzaman, S. M.
AU - Mano, Tadaaki
PY - 1998
Y1 - 1998
N2 - To evaluate the response of vasomotor sympathetic nerve activity to lower body positive pressure (LBPP), muscle sympathetic nerve activity (MSNA) was microneurographically recorded from the tibial nerve in 10 healthy young men, along with hemodynamic variables and echocardiogram, during exposure to incremental LBPP at 10, 20, and 30 mmHg in the supine position. MSNA was suppressed to a similar extent (27%) at 10- and 20-mmHg LBPP. However, at 30- mmHg LBPP, MSNA tended to increase but was still nearly at the control value. Mean arterial pressure was elevated (11%), total peripheral resistance markedly increased (36%), and stroke volume and cardiac output tended to decrease at 30-mmHg LBPP. Heart rate remained unchanged throughout the procedures. Left atrial dimension significantly increased during 10- and 30- mmHg LBPP, indicating an increased cardiac filling. These results suggest that the inhibitory effect of the cardiopulmonary baroreflex on MSNA at 10- and 20-mmHg LBPP could be counteracted by the sympathoexcitatory effect of the intramuscular pressure-sensitive mechanoreflex at 30-mmHg LBPP. However, the increment of total peripheral resistance at 30-mmHg LBPP may not depend exclusively on this small enhancement of MSNA.
AB - To evaluate the response of vasomotor sympathetic nerve activity to lower body positive pressure (LBPP), muscle sympathetic nerve activity (MSNA) was microneurographically recorded from the tibial nerve in 10 healthy young men, along with hemodynamic variables and echocardiogram, during exposure to incremental LBPP at 10, 20, and 30 mmHg in the supine position. MSNA was suppressed to a similar extent (27%) at 10- and 20-mmHg LBPP. However, at 30- mmHg LBPP, MSNA tended to increase but was still nearly at the control value. Mean arterial pressure was elevated (11%), total peripheral resistance markedly increased (36%), and stroke volume and cardiac output tended to decrease at 30-mmHg LBPP. Heart rate remained unchanged throughout the procedures. Left atrial dimension significantly increased during 10- and 30- mmHg LBPP, indicating an increased cardiac filling. These results suggest that the inhibitory effect of the cardiopulmonary baroreflex on MSNA at 10- and 20-mmHg LBPP could be counteracted by the sympathoexcitatory effect of the intramuscular pressure-sensitive mechanoreflex at 30-mmHg LBPP. However, the increment of total peripheral resistance at 30-mmHg LBPP may not depend exclusively on this small enhancement of MSNA.
KW - Cardiopulmonary baroreceptor
KW - Intramuscular pressure-sensitive receptor
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M3 - Article
C2 - 9746473
SN - 0363-6135
VL - 275
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 4 44-4
ER -