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Hypoxic pulmonary vasoconstriction does not limit maximal exercise capacity in healthy volunteers breathing 12% oxygen at sea level.
Talbot, Nick P; Cheng, Hung-Yuan; Hanstock, Helen; Smith, Thomas G; Dorrington, Keith L; Robbins, Peter A.
Affiliation
  • Talbot NP; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
  • Cheng HY; Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.
  • Hanstock H; Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden.
  • Smith TG; Centre for Human and Applied Physiological Sciences, King's College London, London, UK.
  • Dorrington KL; Guy's and St Thomas' NHS Foundation Trust, London, UK.
  • Robbins PA; Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
Physiol Rep ; 12(4): e15944, 2024 Feb.
Article in En | MEDLINE | ID: mdl-38366054
ABSTRACT
Maximal exercise capacity is reduced at altitude or during hypoxia at sea level. It has been suggested that this might reflect increased right ventricular afterload due to hypoxic pulmonary vasoconstriction. We have shown previously that the pulmonary vascular sensitivity to hypoxia is enhanced by sustained isocapnic hypoxia, and inhibited by intravenous iron. In this study, we tested the hypothesis that elevated pulmonary artery pressure contributes to exercise limitation during acute hypoxia. Twelve healthy volunteers performed incremental exercise tests to exhaustion breathing 12% oxygen, before and after sustained (8-h) isocapnic hypoxia at sea level. Intravenous iron sucrose (n = 6) or saline placebo (n = 6) was administered immediately before the sustained hypoxia. In the placebo group, there was a substantial (12.6 ± 1.5 mmHg) rise in systolic pulmonary artery pressure (SPAP) during sustained hypoxia, but no associated fall in maximal exercise capacity breathing 12% oxygen. In the iron group, the rise in SPAP during sustained hypoxia was markedly reduced (3.4 ± 1.0 mmHg). There was a small rise in maximal exercise capacity following sustained hypoxia within the iron group, but no overall effect of iron, compared with saline. These results do not support the hypothesis that elevated SPAP inhibits maximal exercise capacity during acute hypoxia in healthy volunteers.
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Full text: 1 Database: MEDLINE Main subject: Oxygen / Vasoconstriction Limits: Humans Language: En Year: 2024 Type: Article

Full text: 1 Database: MEDLINE Main subject: Oxygen / Vasoconstriction Limits: Humans Language: En Year: 2024 Type: Article