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Impact of increased muscle sympathetic nerve activity on conduit artery shear rate patterns
Author(s) -
Padilla Jaume,
Young Colin N.,
Simmons Grant H.,
Deo Shekhar H.,
Newcomer Sean C.,
Sullivan John P.,
Laughlin M. Harold,
Fadel Paul J.
Publication year - 2010
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.24.1_supplement.1020.13
Subject(s) - cardiology , medicine , blood pressure , brachial artery , microneurography , cold pressor test , artery , heart rate , anesthesia , baroreflex
Disturbed flow patterns induce a proatherogenic endothelial cell phenotype; however, the factors accountable for the oscillatory shear profiles in peripheral conduit arteries are not fully understood. We tested the hypothesis that acute elevations in muscle sympathetic nerve activity (MSNA) are accompanied by increases in conduit artery retrograde shear and oscillatory shear index (OSI). Fourteen healthy men (25±1 yrs) performed three sympatho‐excitatory maneuvers: progressive lower body negative pressure (LBNP) from −10 to −40 Torr, cold pressor test (CPT), and 35% maximal voluntary contraction handgrip followed by postexercise ischemia (PEI). MSNA, arterial blood pressure (BP), and brachial artery velocity and diameter were recorded continuously. All maneuvers elicited significant increases in MSNA total activity from baseline; whereas mean BP was only increased during CPT and PEI (p<0.05). Interestingly, retrograde shear (−3.96±1.2 baseline vs. −8.15±1.8 s −1 −40 LBNP, p<0.05) and OSI (0.09±0.02 baseline vs. 0.20±0.02 a.u. −40 LBNP, p<0.05) were primarily increased during LBNP in which elevated MSNA was not accompanied by increases in BP. Together, these data suggest that elevated MSNA may promote an increase in retrograde and oscillatory shear; however, these effects may be influenced by concomitant changes in BP. Support: NIH RO1HL093167, HL52490