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Attenuated Skeletal Muscle Contraction‐Induced Rapid Onset Vasodilation in African Americans
Author(s) -
Kaur Jasdeep,
Barbosa Thales C.,
Young Benjamin E.,
Stephens Brandi Y.,
Nandadeva Damsara P.,
Brothers R. Matthew,
Fadel Paul J.
Publication year - 2019
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.2019.33.1_supplement.541.19
Subject(s) - forearm , medicine , vasodilation , brachial artery , cardiology , contraction (grammar) , blood pressure , hemodynamics , skeletal muscle , endocrinology , anatomy
A number of studies have demonstrated that African Americans (AA) have a blunted ability to vasodilate at rest compared to Caucasian Americans (CA). Recently, our laboratory has demonstrated that AA have an attenuated forearm vascular conductance (FVC) response to rhythmic handgrip exercise at moderate and high intensities. Whether these differences in vasodilation also occur at the immediate onset of exercise remains unknown. Herein, we tested the hypothesis that AA subjects have an attenuated increase in FVC following a single muscle contraction, compared to CA subjects. A single muscle contraction model was chosen since it allows for isolation of rapid and robust local vasodilatory responses that are independent of large changes in systemic hemodynamics or sympathetic activation. Young, healthy AA (n = 4) and CA (n = 4) men performed single forearm contractions at 20%, 40%, and 60% of their maximum voluntary contraction (MVC). Heart rate (ECG), arterial blood pressure (Finometer), and brachial artery blood flow (duplex Doppler ultrasound) were continuously measured. FVC was calculated as forearm blood flow (FBF)/mean arterial pressure (MAP). Baseline FVC (CA: 1.04 ± 0.18 and AA: 1.31 ± 0.11 ml/min/mmHg; p = 0.26), FBF (CA: 99.5 ± 16.1 and AA: 105.9 ± 8.7 ml/min; p = 0.54), MAP (CA: 82 ± 2 and AA: 84 ± 2 mmHg; p = 0.46) and MVCs (CA: 56 ± 1 and AA: 58 ± 3 kg; p = 0.45) were similar between the groups. Following single forearm contraction, both groups exhibited intensity‐dependent increases in FBF and FVC; however, these responses were significantly attenuated in AA at all intensities compared to CA. For instance, in response to 20% MVC single contractions, AA had a 34 ± 10% increase in FVC from baseline compared to a 86 ± 31% increase in CA (mixed‐model ANOVA; p < 0.001), and in response to 60% MVC single contractions, AA had a 132 ± 9% increase in FVC from baseline compared to a 198 ± 30% in CA (mixed‐model ANOVA; p < 0.001). These preliminary data suggest that AA have blunted vasodilation in response to single forearm contractions at mild, moderate and high‐intensity workloads. Support or Funding Information Supported by UTA College of Nursing and Healthy Innovation This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .