Carotid baroreflex control of leg vasculature in exercising and non-exercising skeletal muscle in humans.
Carotid baroreflex (CBR) function was examined in five men and three women (25 +/- 1 years) using the variable-pressure neck collar technique at rest and during dynamic, one-legged knee extension exercise at 7 W and 25 W. The CBR exhibited control of leg vascular conductance (LVC) at rest and during exercise in both an exercising leg (EL) and a non-exercising leg (NEL) across a wide range of pressures from +40 Torr neck pressure (NP) to -80 Torr neck suction (NS). Specifically, increases in LVC (% change) in response to NS were no different across -20 to -80 Torr in either EL or NEL compared to rest, P > 0.05. However, CBR-mediated decreases in percentage LVC in response to NP were attenuated in EL at both 7 W (16 +/- 1%) and 25 W (12 +/- 1%) compared to rest (40 +/- 3%; P < 0.05) as well as compared to responses in the NEL (36 +/- 6% at 7 W and 36 +/- 7% at 25 W; P < 0.05). This decrease in vascular responsiveness in EL was associated with a reduction in the gain of the percentage muscle sympathetic nerve activity (%MSNA)-%LVC relationship compared to rest (P < 0.05). Collectively, these data indicate that, despite a clear attenuation of the vascular response to MSNA in the exercising leg, CBR-mediated changes in mean arterial pressure were no different between rest and exercise.
Keller
David Melvin
DM
University of North Texas Health Science Center at Fort Worth, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA. davidkeller@texashealth.org
Fadel
Paul J
PJ
Ogoh
Shigehiko
S
Brothers
Robert Matthew
RM
Hawkins
Megan
M
Olivencia-Yurvati
Al
A
Raven
Peter B
PB
D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002344:Carotid Body / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007717:Knee / Q000502:physiology; D007866:Leg / Q000098:blood supply / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000502:physiology*; D012146:Rest / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology