title: Reduced spontaneous sympathetic nerve activity in multiple sclerosis patients.
abstract: For the first time, we obtained direct intra-neural measurements of muscle sympathetic nerve activity (MSNA) in relapsing-remitting multiple sclerosis (MS) patients to test the hypothesis that spontaneous resting MSNA is reduced in MS patients compared to age, sex-matched healthy controls. Spontaneous MSNA (microneurography; peroneal nerve), plasma norepinephrine, arterial blood pressure (finger photoplethysmography), and heart rate were measured at rest in three groups: 1) relapsing-remitting MS patients on disease modifying therapy only (MS-DT; n=6); 2) relapsing-remitting MS patients on disease modifying therapy and medications for MS-related symptoms that are known to effect the central nervous system (MS-DT/ST; n=5), and 3) healthy age and sex-matched controls (CON; n=6). Compared to the CON group, MSNA burst frequency (bursts/min) was significantly lower in both MS-DT (P=0.027) and MS-DT/ST groups (P=0.003). Similarly, MSNA burst incidence (bursts/100 heartbeats) was significantly reduced in both MS-DT (P=0.049) and MS-DT/ST groups (P=0.004) compared to the CON group. Burst frequency and burst incidence were not different between MS-DT and MS-DT/ST groups. Resting plasma norepinephrine was also significantly lower in both MS-DT (P=0.039) and MS-DT/ST groups (P=0.021) compared to the CON group. Reduced MSNA may signify an important dysfunction in autonomic control of cardiovascular function in patients with MS.
authors.affiliation: Department of Kinesiology, University of Texas at Arlington, Arlington, TX, United States.
authors.forename: David M
authors.initials: DM
authors.lastname: Keller
authors.affiliation: Department of Medical Pharmacology & Physiology, University of Missouri, Columbia, MO, United States; Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Fadel
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Harnsberger
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Remington
authors.affiliation: Department of Neurology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States; Department of Ophthalmology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States.
authors.forename: Elliot M
authors.initials: EM
authors.lastname: Frohman
authors.affiliation: Department of Applied Physiology & Wellness, Southern Methodist University, Dallas, TX, United States; Department of Neurology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States. Electronic address: sldavis@smu.edu.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Davis
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000097:blood / Q000473:pathology*; D009638:Norepinephrine / Q000097:blood; D013564:Sympathetic Nervous System / Q000503:physiopathology*
chemical_list: D009638:Norepinephrine
keywords: Autonomic dysfunction; Blood pressure; Microneurography; Muscle sympathetic nerve activity; Peripheral vasculature; Plasma norepinephrine