Control of skin sympathetic nerve activity during intermittent static handgrip exercise.
BACKGROUND
Exercise activates the sympathetic nervous system as a function of the type and intensity of exercise and of the target organ studied. Although central command and activity of metabolically sensitive afferents from exercising muscle are the principal determinants of sympathetic outflow directed to skeletal muscle, the mechanisms that govern sympathetic outflow directed to skin are less clear.


RESULTS
We measured skin sympathetic nerve activity (SSNA) during intermittent static handgrip (SHG; at 45% of maximal voluntary contraction; four 5-second contractions per minute for 3 minutes), during unrestricted forearm perfusion (control), during stimulation of forearm mechanoreceptors with venous congestion, and during ischemia produced by forearm circulatory arrest. Under all 3 conditions, SSNA increased within 1 to 2 seconds of the onset of handgrip. During ischemia but not during venous congestion, SSNA increased more compared with control (P<0.05) and remained elevated when forearm ischemia was maintained after handgrip exercise (posthandgrip circulatory arrest). In addition, simulated handgrip and intermittent forearm compression produced by a pneumatic cuff also evoked brief increases of SSNA.


CONCLUSIONS
In addition to central neural factors, afferent input from exercising muscle plays an important role in modulating sympathetic outflow directed to skin.
Department of Medicine, Division of Cardiology, Pennsylvania State College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA. uleuenberger@psu.edu
Urs A
UA
Leuenberger
Sogol
S
Mostoufi-Moab
Michael
M
Herr
Kristen
K
Gray
Allen
A
Kunselman
Lawrence I
LI
Sinoway
D000328:Adult; D005260:Female; D005542:Forearm / Q000098:blood supply; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007511:Ischemia / Q000503:physiopathology; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology; D010543:Peroneal Nerve / Q000502:physiology; D012867:Skin / Q000098:blood supply / Q000294:innervation*; D013564:Sympathetic Nervous System / Q000502:physiology*; D014111:Tourniquets; D014680:Veins / Q000503:physiopathology