Original Article

Journal of Human Hypertension (2014) 28, 438–443; doi:10.1038/jhh.2013.128; published online 9 January 2014

Attenuated NOx responses and myocardial ischemia, a possible risk for structural vascular disease in African men: the SABPA study

A S Uys1, L Malan1, J M van Rooyen1, H S Steyn2, M Reimann3 and T Ziemssen3

  1. 1Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa
  2. 2Statistical Consultation Services, North-West University, Potchefstroom, South Africa
  3. 3Department of Neurology, University Hospital Carl Gustav Carus, Dresden University of Technology, Dresden, Germany

Correspondence: Dr AS Uys, Hypertension in Africa Research Team (HART), North-West University, Potchefstroom Campus, Private Bag x6001, Potchefstroom 2520, South Africa. E-mail: Lisa.Uys@nwu.ac.za

Received 2 July 2013; Revised 17 October 2013; Accepted 6 November 2013
Advance online publication 9 January 2014

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Abstract

Chronically elevated blood pressure has been associated with impaired NO-mediated vasodilation and structural vascular disease risk. This study aimed to determine whether significant associations exist regarding NO metabolite (NOx) responses, cardiovascular function and structural vascular disease in a cohort of African and Caucasian men. The study included 81 African and 94 Caucasian male teachers stratified via median splits into low and high NOx ethnic groups. Ambulatory blood pressure, electrocardiogram monitoring and ultrasound carotid intima-media thickness (CIMT) images were obtained. Cardiovascular measurements and fasting blood for NOx responses were measured during rest and on challenging the cardiovascular system with the Stroop colour-word conflict test. African men displayed significantly higher resting NOx as well as higher number of 24h silent ischemic events than their Caucasian counterparts. Low NOx African men displayed enhanced α-adrenergic and ECG ST segment depression acute mental stress responses as well as 24h silent ischemic events associated with CIMT (adjusted R2=0.47; β=0.25; confidence interval (CI)=0.13, 0.41). African men demonstrated a vulnerable cardiovascular profile. Novel findings revealed α-adrenergic-driven blood pressure responses and less NO bioavailability during acute stress. The association between myocardial ischemia and CIMT in this group emphasized their risk for future coronary artery disease and cerebrovascular events.

Keywords:

African; cardiovascular function; myocardial ischemia; nitric oxide; structural vascular disease

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