Intensified large artery and microvascular response to cold adrenergic stimulation in African blacks.
BACKGROUND
Arterial stiffening is more accelerated in blacks than in whites. Whether this is attributed to an enhanced vascular reactivity to environmental stress stimulation remains unknown. We therefore decided to test the hypothesis that cold pressor test (CPT) elicits a greater increase in arterial stiffness and an enhanced sympathetic skin vasoconstriction in African blacks than in whites normotensives.


METHODS
A total of 17 young normotensive African blacks and 17 normotensive whites were recruited. All underwent continuous assessment of blood pressure (BP), heart rate, and carotid-femoral pulse wave velocity (PWVc-f) at rest, during and after hand immersion in iced water (CPT). Concomitantly, skin microvascular blood flow was monitored by laser Doppler flowmetry on the opposite hand.


RESULTS
At baseline, African blacks exhibited higher values of PWVc-f than whites (7.2 +/- 0.3 vs. 6.5 +/- 0.2 m/s, respectively, P = 0.04). During CPT the increases in systolic BP and PWVc-f were greater in African blacks than in whites (systolic BP 17 +/- 2 mm Hg vs. 9 +/- 3 mm Hg, P < 0.001 and PWVc-f 0.62 +/- 0.1 m/s vs. 0.26 +/- 0.1 m/s, P = 0.03, respectively). However, there was no significant difference in the PWVc-f responses among the groups during CPT after adjustment for the increments in mean BP. Finally, CPT induced a more pronounced skin microvascular vasoconstriction in African blacks than in whites (-54.4 +/- 5 % vs. -31.3 +/- 6 %, P < 0.001).


CONCLUSIONS
CPT provokes a more pronounced increase in PWVc-f in normotensive African blacks than in whites, that appears to be due to a greater increase in mean BP. Additionally, African blacks present an intensified skin microvascular response to the CPT as compared to their whites counterparts.
Adamopoulos
Dionysios
D
Department of Cardiology, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium. adamopoulos1@gmail.com
Ngatchou
William
W
Lemogoum
Daniel
D
Janssen
Christophe
C
Beloka
Sofia
S
Lheureux
Oliver
O
Kayembe
Patricia
P
Argacha
Jean-François
JF
Degaute
Jean-Paul
JP
van de Borne
Philippe
P
D000328:Adult; D000349:Africa / Q000208:ethnology; D044383:Black People; D001794:Blood Pressure / Q000502:physiology*; D002339:Carotid Arteries / Q000502:physiology; D003080:Cold Temperature; D004548:Elasticity; D005263:Femoral Artery / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D011674:Pulse; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D014661:Vasoconstriction; D044465:White People