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Sympathetic vascular transduction following spontaneous MSNA bursts is augmented in young black men
Author(s) -
Credeur Daniel Paul,
Holwerda Seth W,
Fairfax Seth T,
Keller David M,
Fadel Paul J
Publication year - 2013
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.27.1_supplement.1117.3
Subject(s) - microneurography , medicine , vasoconstriction , cardiology , blood pressure , vasodilation , baroreflex , heart rate
Young blacks exhibit an augmented vasoconstrictor response to α‐adrenergic agonists compared to whites. Whether this increase in α‐adrenergic receptor sensitivity in blacks evokes greater vasoconstriction to spontaneous bursts of muscle sympathetic nerve activity (MSNA) is unknown. Thus, in fourteen young normotensive black (N=7) and white men (N=7), MSNA (microneurography) and femoral artery blood flow (duplex Doppler ultrasound) were continuously measured for 20 minutes under resting conditions. Signal averaging was used to characterize beat‐by‐beat changes in leg vascular conductance (LVC) for 15 cardiac cycles following each individual MSNA burst. Variations in MSNA burst pattern (single vs. multiple successive bursts) and burst size (height) were considered. Blacks demonstrated a significantly greater reduction in LVC following single (blacks: −11.2±1.7 vs. whites: −4.6±1.24%; P<0.05) as well as multiple MSNA bursts (blacks: −19.4±2.0 vs. whites: −13.2±1.6; P<0.05). In addition, increases in burst height evoked graded reductions in LVC in both groups, with blacks having significant greater reductions in LVC. These preliminary findings suggest an augmented sympathetic vascular transduction in young normotensive blacks in response to spontaneous bursts of MSNA. Supported by NIH Grant R15HL096103 (DMK) and RO1 HL093167 (PJF)