title: Effects of acute and chronic stress on the L-arginine nitric oxide pathway in black and white South Africans: the sympathetic activity and ambulatory blood pressure in Africans study.
abstract: OBJECTIVE
  This study investigated the impact of stress on effectors of the L-arginine/nitric oxide (NO) system including the endogenous inhibitor asymmetric dimethylarginine (ADMA).
  
  
  METHODS
  Black (n = 168) and white (n = 206) South African teachers were exposed to a mental and a physical stressor for 1 minute, respectively. Serum samples for determination of l-arginine, NO metabolites, ADMA, and symmetric dimethylarginine (SDMA) were obtained at rest and during stress exposure. Perception of task stressfulness was assessed on a 7-point Likert scale, and psychological distress was estimated by the General Health Questionnaire.
  
  
  RESULTS
  Black South Africans exhibited higher resting levels of NO metabolites (adjusted mean [standard error of the mean] = 11.3 [1.3] versus 3.9 [1.1] μmol/l, p < .001) but lower circulating ADMA (0.62 [0.02] versus 0.70 [0.02] μmol/l, p = .004) and SDMA (0.41 [0.01] versus 0.53 [0.01] μmol/l, p < .001) than did white South Africans. Ethnicity-by-psychological distress interaction was observed for resting levels of ADMA (p = .002), SDMA (p = .038), and L-arginine (p = .048). Ethnic differences in responses to experimental stress were evident for NO metabolites (blacks versus whites: 5.94 [1.55] versus -0.74 [1.25] μmol/l, p = .004) and SDMA (blacks versus whites: -0.02 [0.01] versus 0.02 [0.01] μmol/l, p = .004). Ethnicity-by-psychological distress interaction for stress responses was found for l-arginine/ADMA ratio (p = .027).
  
  
  CONCLUSIONS
  The l-arginine/NO system is affected by psychosocial distress with higher susceptibility in black South Africans. This interaction may contribute to the higher cardiovascular disease risk in black South Africans.
authors: Autonomic and Neuroendocrinological Laboratory Dresden, Department of Neurology, University Hospital Carl Gustav Carus at the Dresden University of Technology, Fetscherstr. 74, 01307 Dresden, Germany. manja.reimann@uniklinikum-dresden.de.
authors: Manja
authors: M
authors: Reimann
authors: Mark
authors: M
authors: Hamer
authors: Nicolaas T
authors: NT
authors: Malan
authors: Markus P
authors: MP
authors: Schlaich
authors: Gavin W
authors: GW
authors: Lambert
authors: Tjalf
authors: T
authors: Ziemssen
authors: Rainer H
authors: RH
authors: Boeger
authors: Leoné
authors: L
authors: Malan
mesh_terms: D000208:Acute Disease; D000328:Adult; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism*; D044383:Black People / Q000523:psychology / Q000706:statistics & numerical data*; D001794:Blood Pressure / Q000502:physiology; D018660:Blood Pressure Monitoring, Ambulatory; D002318:Cardiovascular Diseases / Q000208:ethnology / Q000378:metabolism; D002908:Chronic Disease; D003080:Cold Temperature / Q000009:adverse effects; D003430:Cross-Sectional Studies; D004198:Disease Susceptibility / Q000208:ethnology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D011312:Pressure / Q000009:adverse effects; D012146:Rest / Q000502:physiology; D013019:South Africa; D013315:Stress, Psychological / Q000208:ethnology / Q000378:metabolism*; D057190:Stroop Test; D044465:White People / Q000706:statistics & numerical data
chemical_list: D009569:Nitric Oxide; C024917:symmetric dimethylarginine; C018524:N,N-dimethylarginine; D001120:Arginine
keywords: African; asymmetric dimethylarginine; cold pressor test; distress; l-arginine/nitric oxide pathway