title: Carotid baroreflex regulation of sympathetic nerve activity during dynamic exercise in humans.
abstract: We sought to determine whether carotid baroreflex (CBR) control of muscle sympathetic nerve activity (MSNA) was altered during dynamic exercise. In five men and three women, 23.8 +/- 0.7 (SE) yr of age, CBR function was evaluated at rest and during 20 min of arm cycling at 50% peak O(2) uptake using 5-s periods of neck pressure and neck suction. From rest to steady-state arm cycling, mean arterial pressure (MAP) was significantly increased from 90.0 +/- 2.7 to 118.7 +/- 3.6 mmHg and MSNA burst frequency (microneurography at the peroneal nerve) was elevated by 51 +/- 14% (P < 0.01). However, despite the marked increases in MAP and MSNA during exercise, CBR-Delta%MSNA responses elicited by the application of various levels of neck pressure and neck suction ranging from +45 to -80 Torr were not significantly different from those at rest. Furthermore, estimated baroreflex sensitivity for the control of MSNA at rest was the same as during exercise (P = 0.74) across the range of neck chamber pressures. Thus CBR control of sympathetic nerve activity appears to be preserved during moderate-intensity dynamic exercise.
authors.affiliation: Department of Integrative Physiology and Cardiovascular Research Institute, University of North Texas Health Science Center, Fort Worth, Texas 76107, USA. paul.fadel@utsouthwestern.edu
authors.forename: P J
authors.initials: PJ
authors.lastname: Fadel
authors.forename: S
authors.initials: S
authors.lastname: Ogoh
authors.forename: D E
authors.initials: DE
authors.lastname: Watenpaugh
authors.forename: W
authors.initials: W
authors.lastname: Wasmund
authors.forename: A
authors.initials: A
authors.lastname: Olivencia-Yurvati
authors.forename: M L
authors.initials: ML
authors.lastname: Smith
authors.forename: P B
authors.initials: PB
authors.lastname: Raven
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology*; D002346:Carotid Sinus / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009333:Neck / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000502:physiology*