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Holwerda SW, Samels MR, Keller DM. Carotid baroreflex responsiveness in normotensive African Americans is attenuated at rest and during dynamic leg exercise. Front Physiol. 2013;4:29doi: 10.3389/fphys.2013.00029.
Holwerda, S. W., Samels, M. R., & Keller, D. M. (2013). Carotid baroreflex responsiveness in normotensive African Americans is attenuated at rest and during dynamic leg exercise. Frontiers in physiology, 429. https://doi.org/10.3389/fphys.2013.00029
Holwerda, Seth W, et al. "Carotid baroreflex responsiveness in normotensive African Americans is attenuated at rest and during dynamic leg exercise." Frontiers in physiology vol. 4 (2013): 29. doi: https://doi.org/10.3389/fphys.2013.00029
Holwerda SW, Samels MR, Keller DM. Carotid baroreflex responsiveness in normotensive African Americans is attenuated at rest and during dynamic leg exercise. Front Physiol. 2013 Mar 08;4:29. doi: 10.3389/fphys.2013.00029. eCollection 2013. PMID: 23482843; PMCID: PMC3591748.
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Front Physiol. 2013 Mar 08;4:29. doi: 10.3389/fphys.2013.00029. eCollection 2013.

Carotid baroreflex responsiveness in normotensive African Americans is attenuated at rest and during dynamic leg exercise.

Frontiers in physiology

Seth W Holwerda, Mitchel R Samels, David M Keller

Affiliations

  1. Department of Medical Pharmacology and Physiology, University of Missouri Columbia, SC, USA.

PMID: 23482843 PMCID: PMC3591748 DOI: 10.3389/fphys.2013.00029

Abstract

Evidence suggests differences between African Americans (AAs) and Caucasian Americans (CAs) in cardiovascular responsiveness to physiological stressors. This study tested the hypothesis that carotid baroreflex (CBR) control of heart rate (HR) and blood pressure is reduced in AAs compared to CAs during exercise. Mean arterial pressure (MAP) and HR were continuously recorded at rest and during leg cycling in 23 non-hypertensive male subjects (12 AA; 11 CA; age 19-26 years). CBR control of HR and MAP was assessed with 5-s pulses of neck pressure (NP, simulated hypotension) and neck suction (NS, simulated hypertension) ranging from +45 to -80 Torr. Across all NS stimuli (-20, -40, -60, -80 Torr) at rest, the AA group demonstrated attenuated CBR-mediated reductions in HR (AA, -8.9 ± 1.9 vs. CA, -14.1 ± 2.3 bpm; P < 0.001) and MAP (AA, -6.4 ± 1 vs. CA, -7.8 ± 0.8 mmHg; P < 0.05). Despite similar gain and magnitude of resetting observed in the modeled stimulus response curves, an attenuation among AAs persisted in HR (AA, -8.2 ± 1.6 vs. CA, -11.8 ± 3 bpm; P < 0.05) and MAP (AA, -6.8 ± 0.9 vs. CA, -8.2 ± 1.1 mmHg; P < 0.05) responses to NS during exercise. No differences in CBR-mediated HR and MAP responses to NP were detected between groups at rest or during exercise. These data suggest impairment in the ability to defend against a hypertensive challenge among AAs during steady-state exercise compared to their CA counterparts.

Keywords: blood pressure; exercise; heart rate; hypertension; racial differences

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