title: Carotid baroreflex control of leg vasculature in exercising and non-exercising skeletal muscle in humans.
abstract: 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.
authors.affiliation: University of North Texas Health Science Center at Fort Worth, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA. davidkeller@texashealth.org
authors.forename: David Melvin
authors.initials: DM
authors.lastname: Keller
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Fadel
authors.forename: Shigehiko
authors.initials: S
authors.lastname: Ogoh
authors.forename: Robert Matthew
authors.initials: RM
authors.lastname: Brothers
authors.forename: Megan
authors.initials: M
authors.lastname: Hawkins
authors.forename: Al
authors.initials: A
authors.lastname: Olivencia-Yurvati
authors.forename: Peter B
authors.initials: PB
authors.lastname: Raven
mesh_terms: 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