Effects of tetrahydrobiopterin on venous bubble grade and acute diving-induced changes in cardiovascular function.
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.
Glavas
Duska
D
Department of Internal Medicine, University Hospital Split, Split, Croatia.
Bakovic
Darija
D
Obad
Ante
A
Palada
Ivan
I
Breskovic
Toni
T
Valic
Zoran
Z
Brubakk
Alf O
AO
Dujic
Zeljko
Z
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
D000975:Antioxidants; D005740:Gases; D001708:Biopterins; C003402:sapropterin; D001205:Ascorbic Acid