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Blood pressure responses to skeletal muscle contraction relative to salt sensitivity in humans and rats (1165.11)
Author(s) -
Matthews Evan,
Stocker Sean,
Brian Michael,
Wenner Megan,
Edwards David,
Farquhar William
Publication year - 2014
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.28.1_supplement.1165.11
Subject(s) - endocrinology , medicine , contraction (grammar) , stimulation , blood pressure , sodium , chemistry , skeletal muscle , afferent , mean arterial pressure , heart rate , organic chemistry
Salt sensitivity of blood pressure (BP) is linked to increased mortality. Salt sensitive (SS) rats display exaggerated BP responses to muscle afferent stimulation, a finding not yet studied in humans. We hypothesized that SS adults would have greater BP responses to muscle contraction than salt resistant (SR) adults. To define salt sensitivity status, a median split of 24hr mean BP (MAP) responses (%∆) to dietary sodium (20 mmol/d x 7 d to 300 mmol/d x 7 d sodium) was used in 12 adults and resulted in 6 SS (6.4±1.5 %∆) and 6 SR (‐0.1±1.6 %∆ p<0.05). Static handgrip (HG; 2 min 40% maximal voluntary contraction) was performed during normal sodium intake. MAP responses to HG tended to be greater in SS than SR (30.2±5.1 vs. 16.7±4.0 %∆, p=0.06). Salt induced %∆MAP was correlated to HG %∆MAP (r=0.658 p<0.05). Parallel experiments in Dahl SS (DSS, n=4) & Dahl SR (DSR, n=4) rats fed 0.1% NaCl confirms that stimulation of sciatic afferent nerves (500uA, 5Hz, 1ms pulse) produce greater increases in MAP (SS 26±4; SR 15±2 mmHg, p<0.05). Additionally we found greater renal sympathetic nerve activity (SS 175±12; SR 147±8 %, p<0.05). These preliminary data suggest greater BP responses to muscle contraction in SS humans & rats due to greater sympathetic activity; this may be a factor in the poorer CV outcomes in SS adults. Grant Funding Source : Supported by NIH R01 HL104106, NIH R01HL113270 and AHA EIA, & ACSM Foundation Research Grant.