title: Autonomic activity and leptin in Africans and whites: the SABPA study.
abstract: OBJECTIVE
  Evidence exists that leptin enhances sympathetic activity and may thereby contribute to the development of obesity-related hypertension. Sympathetic activation also seems more prominent in Africans than whites. We compared leptin levels, and different markers of autonomic activity between Africans and whites, and determined whether a relationship exists between leptin and autonomic activity.
  
  
  METHODS
  The study included 409 African and white school teachers (aged, 44.6 ± 9.6 years). We determined leptin in serum and measured ambulatory blood pressure. Markers reflecting autonomic activity included renin, cortisol, baroreflex sensitivity, ambulatory heart rate and heart rate variability (HRV) components (assessed by 24-h ECG recordings in the frequency and geometric domain).
  
  
  RESULTS
  Africans had higher leptin levels, BMI, blood pressure and heart rate (all P < 0.001) as well as lower HRV triangular index and HRV total power (P < 0.001). After also adjusting for BMI in multivariate regression analyses, in African men, renin (β = 0.228; P = 0.033), night-time heart rate (β = 0.184; P = 0.034), HRV triangular index (β = -0.230; P = 0.010) and HRV total power (β = -0.214; P = 0.046) associated with leptin. In white men, leptin associated with 24-h heart rate (β = 0.376; P < 0.001), as well as day and night-time heart rate (both P < 0.01), HRV triangular index (β = -0.335; P < 0.001) and HRV total power (β = -0.403; P < 0.001). In African women, we observed an association of leptin with the total power component of HRV (β = -0.221; P = 0.015) and a borderline association with renin (β = 0.219; P = 0.057). No significant associations were apparent in the white women.
  
  
  CONCLUSIONS
  We found that leptin is independently associated with different markers of autonomic activity, especially in men.
authors: Hypertension in Africa Research Team, North-West University, Potchefstroom, South Africa.
authors: Chiné
authors: C
authors: Pieterse
authors: Rudolph
authors: R
authors: Schutte
authors: Aletta E
authors: AE
authors: Schutte
mesh_terms: D000328:Adult; D000349:Africa; D000886:Anthropometry; D001341:Autonomic Nervous System / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D044383:Black People; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D020738:Leptin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D044465:White People
chemical_list: D015415:Biomarkers; D020738:Leptin