title: Asymmetric dimethylarginine attenuates the association of melatonin secretion with night-time blood pressure and dipping in elderly individuals.
abstract: BACKGROUND
  Melatonin decreases night-time blood pressure (BP) by increasing nitric oxide (NO) in endothelial cells. Whether serum asymmetric dimethylarginine (ADMA), a major endogenous competitive inhibitor of endothelial NO synthase, attenuates the association of melatonin with night-time BP and dipping in humans is unclear. METHODS AND RESULTS: In this cross-sectional study of 852 community-based elderly individuals, serum ADMA, overnight urinary 6-sulfatoxymelatonin excretion (UME), and ambulatory BP were measured. Mean ADMA was 0.46±0.06 μmol/L. In the low-ADMA group (n=451), crude OR for nocturnal hypertension (NH) and non-dipper significantly decreased with a quartile increase in UME (P=0.023 and 0.001, respectively), but these associations were not observed in the high-ADMA group (n=401). Higher UME was significantly and inversely associated with adjusted OR for NH and non-dipper in the low-ADMA group (Q1, 1.00 and 1.00; Q2, 0.92 and 0.74; Q3, 0.57 and 0.51; Q4, 0.48 and 0.40; P=0.004 and 0.002, respectively) but not in the high-ADMA group (P=0.75 and 0.12, respectively). These association trends were also observed on continuous variable analysis (low ADMA, P=0.031 and 0.003; high ADMA, P=0.52 and 0.13; respectively).
  
  
  CONCLUSIONS
  ADMA attenuates the association of endogenous melatonin with night-time BP and dipping in the general elderly population.
authors.affiliation: Department of Community Health and Epidemiology, Nara Medical University School of Medicine.
authors.forename: Kenji
authors.initials: K
authors.lastname: Obayashi
authors.forename: Keigo
authors.initials: K
authors.lastname: Saeki
authors.forename: Norio
authors.initials: N
authors.lastname: Kurumatani
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001120:Arginine / Q000031:analogs & derivatives* / Q000097:blood / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D015992:Body Mass Index; D002940:Circadian Rhythm / Q000502:physiology*; D003430:Cross-Sectional Studies; D003920:Diabetes Mellitus / Q000097:blood / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000378:metabolism; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology; D008297:Male; D008550:Melatonin / Q000031:analogs & derivatives / Q000378:metabolism* / Q000652:urine; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D012636:Secretory Rate; D012907:Smoking / Q000097:blood
chemical_list: C054513:6-sulfatoxymelatonin; D009569:Nitric Oxide; C018524:N,N-dimethylarginine; D001120:Arginine; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D008550:Melatonin