title: Both nitric oxide and endothelin-1 influence cerebral blood flow velocity at rest and after hyper- and hypocapnic stimuli in hypertensive and healthy adolescents.
abstract: OBJECTIVE
  Nitric oxide (NO)/endothelin imbalance may play a role in the regulation of cerebral blood flow. The aim of the present study was to assess whether these endothelial factors influence middle cerebral artery blood flow velocities (MCAV) and cerebrovascular reactivity (CVR) in healthy and hypertensive adolescents.
  
  
  METHODS
  106 adolescents (61 hypertensive and 45 normotensive) underwent transcranial Doppler measurements of the middle cerebral artery at rest and after 30 s of breath-holding (BH) and 60 s of hyperventilation (HV). Additionally, NO and endothelin-1 (ET-1) concentrations of the serum were assessed. The correlation between NO and ET-1 levels as well as MCAV and CVR values was analyzed.
  
  
  RESULTS
  Resting MCAVs were higher among hypertensive teenagers (76.5 +/- 24 vs. 62.8 +/- 15.6 cm/s, respectively, p < 0.001). CVR values did not differ between hypertensive and healthy adolescents after the BH and HV procedure. A significant negative correlation was found between absolute MCAV values and NO concentrations. ET-1 was positively related to MCAV.
  
  
  CONCLUSIONS
  Cerebral blood flow velocities, but not CVR values, are associated with serum NO and ET-1 concentrations in adolescents.
authors.affiliation: First Department of Medicine, Health and Medical Centre, University of Debrecen, Debrecen, Hungary.
authors.forename: Eva
authors.initials: E
authors.lastname: Katona
authors.forename: Georgios
authors.initials: G
authors.lastname: Settakis
authors.forename: Zsuzsa
authors.initials: Z
authors.lastname: Varga
authors.forename: Mária
authors.initials: M
authors.lastname: Juhász
authors.forename: Gyorgy
authors.initials: G
authors.lastname: Paragh
authors.forename: Dániel
authors.initials: D
authors.lastname: Bereczki
authors.forename: Béla
authors.initials: B
authors.lastname: Fulesdi
authors.forename: Dénes
authors.initials: D
authors.lastname: Páll
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001921:Brain / Q000098:blood supply; D019332:Endothelin-1 / Q000097:blood*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000503:physiopathology*; D006985:Hyperventilation / Q000097:blood / Q000503:physiopathology; D016857:Hypocapnia / Q000097:blood / Q000503:physiopathology; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000502:physiology*; D009569:Nitric Oxide / Q000097:blood*; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods
chemical_list: D019332:Endothelin-1; D009569:Nitric Oxide