title: Effects of tetrahydrobiopterin on venous bubble grade and acute diving-induced changes in cardiovascular function.
abstract: BACKGROUND
  Self-contained underwater breathing apparatus diving reduces cardiovascular function and increases pulmonary artery pressure (PAP) up to 3 days after a single dive. Acute antioxidants partially attenuated arterial endothelial dysfunction, whereas cardiac and PA functions were unaffected. We tested the hypothesis that acute tetrahydobiopterin (BH(4)), as a cofactor of endothelial nitric oxide (NO) synthase, reduces bubble grade (BG) and attenuates alteration in cardiovascular function after diving because of increased NO bioavailability.
  
  
  METHODS
  Mean PAP (mPAP), PA acceleration time and right ventricle ejection time, left ventricle ejection fraction (LV-EF) and BG were measured after oral placebo (P), vitamin C (C) or a combination of vitamin C and BH(4) (BH(4)) in a randomized, placebo controlled trial before and after field dive to 30 m of sea water for 30 min bottom time.
  
  
  RESULTS
  Eight recreational divers performed three dives with a 3-days period between them. Regarding the primary hypothesis, no difference was observed between post-dive changes in BG (2.1 +/- 2.2 bubbles cm(-2) for P, 3.4 +/- 3.9 for C and 3.6 +/- 2.1 for BH(4)), mPAP (25.6 +/- 6.5 mmHg for P, 25.9 +/- 8.6 for C and 22.6 +/- 3.5 for BH(4)) and LV-EF (62.6 +/- 4.6% for P, 61.4 +/- 3.9 for C and 61.6 +/- 3.7 for BH(4)) with all three conditions.
  
  
  CONCLUSIONS
  This suggests that co-administration of BH(4) and vitamin C does not improve heart and pulmonary artery function after diving.
authors.affiliation: Department of Internal Medicine, University Hospital Split, Split, Croatia.
authors.forename: Duska
authors.initials: D
authors.lastname: Glavas
authors.forename: Darija
authors.initials: D
authors.lastname: Bakovic
authors.forename: Ante
authors.initials: A
authors.lastname: Obad
authors.forename: Ivan
authors.initials: I
authors.lastname: Palada
authors.forename: Toni
authors.initials: T
authors.lastname: Breskovic
authors.forename: Zoran
authors.initials: Z
authors.lastname: Valic
authors.forename: Alf O
authors.initials: AO
authors.lastname: Brubakk
authors.forename: Zeljko
authors.initials: Z
authors.lastname: Dujic
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage; D001205:Ascorbic Acid / Q000008:administration & dosage; D001708:Biopterins / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D001916:Brachial Artery / Q000187:drug effects / Q000503:physiopathology; D018592:Cross-Over Studies; D003665:Decompression Sickness / Q000517:prevention & control; D004242:Diving; D004311:Double-Blind Method; D004562:Electrocardiography; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology; D005740:Gases / Q000097:blood*; D006321:Heart / Q000187:drug effects* / Q000503:physiopathology; D006352:Heart Ventricles / Q000187:drug effects; D006801:Humans; D008297:Male; D011651:Pulmonary Artery / Q000187:drug effects* / Q000503:physiopathology
chemical_list: D000975:Antioxidants; D005740:Gases; D001708:Biopterins; C003402:sapropterin; D001205:Ascorbic Acid