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Arterial baroreflex control of muscle sympathetic nerve activity during dynamic exercise in humans
Author(s) -
Ogoh Shigehiko,
Fisher James P,
Fadel Paul J,
Raven Peter B
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a573-b
Subject(s) - baroreflex , reflex , blood pressure , medicine , cardiology , heart rate , sympathetic nervous system , anesthesia
Previously, we demonstrated that carotid baroreflex control of sympathetic nerve activity (SNA) was reset to function at the higher arterial pressures induced by arm cycling without a change in reflex sensitivity. More recently a study in animals also indicated exercise resetting of the arterial baroreflex control of SNA; however, significant increases in reflex gain were reported. Whether reflex gain differences are due to species or methodological approaches remains unclear. Therefore, we sought to determine arterial baroreflex (ABR; aortic and carotid) control of SNA during dynamic exercise in humans. Six subjects performed 20 min of 50% peak O 2 uptake arm cycling. ABR control of muscle SNA (MSNA) was evaluated by analyzing the relationship between spontaneous variations in diastolic pressure (DBP) and MSNA. Steady‐state arm cycling increased MSNA burst frequency (P=0.012), burst incidence (P=0.034) and total activity (P=0.01). The linear relationship between DBP and MSNA burst incidence shifted rightward and upward during exercise without any change in sensitivity (slope −4.32±0.70 rest vs. −3.37±0.39 exercise bursts/100 heartbeats/mmHg, P=0.252). Similar results were found for the relationship between DBP and MSNA total activity. These findings indicate that arterial baroreflex control of MSNA is reset without a change in sensitivity during dynamic exercise in humans. Supported by APS RCE Award