title: Does High Alveolar Fluid Reabsorption Prevent HAPE in Individuals with Exaggerated Pulmonary Hypertension in Hypoxia?
abstract: An exaggerated increase in pulmonary arterial systolic pressure (PAsP) is a highlight of high altitude pulmonary edema (HAPE). However, the incidence of HAPE at 4559 m was much lower in altitude-naïve individuals with exaggerated pulmonary vasoconstriction (HPV) in normobaric hypoxia than in known HAPE-susceptibles, indicating that elevated PAsP alone is insufficient to induce HAPE. A decreased nasal potential difference (NPD) has been found in HAPE-susceptibles, where, based on animal models, NPD serves as surrogate of alveolar epithelial ion transport. We hypothesize that those HAPE-resistant individuals with high HPV may be protected by elevated alveolar Na and fluid reabsorption, which might be detected as increased NPD. To test this hypothesis, we measured NPD in normoxia of subjects who were phenotyped in previous studies as high altitude tolerant (controls), known HAPE-susceptibles with high HPV (HP+HAPE), as well as individuals with high HPV but without HAPE (HP-no-HAPE) at 4559 m. NPD and amiloride-sensitive NPD were lower in HP+HAPE than in controls, whereas HP-no-HAPE were not different from either group. There were no differences in Cl-transport between groups. Our results show low nasal ion transport in HAPE but higher transport in those individuals with the highest HPV but without HAPE. This indicates that in some individuals with high PAsP at high altitude high alveolar fluid reabsorption might protect them from HAPE.
authors.affiliation: 1 Medical Clinic VII, Sports Medicine, University of Heidelberg , Heidelberg, Germany .
authors.forename: Theresa
authors.initials: T
authors.lastname: Betz
authors.affiliation: 1 Medical Clinic VII, Sports Medicine, University of Heidelberg , Heidelberg, Germany .
authors.forename: Christoph
authors.initials: C
authors.lastname: Dehnert
authors.affiliation: 1 Medical Clinic VII, Sports Medicine, University of Heidelberg , Heidelberg, Germany .
authors.forename: Peter
authors.initials: P
authors.lastname: Bärtsch
authors.affiliation: 1 Medical Clinic VII, Sports Medicine, University of Heidelberg , Heidelberg, Germany .
authors.forename: Kai
authors.initials: K
authors.lastname: Schommer
authors.affiliation: 1 Medical Clinic VII, Sports Medicine, University of Heidelberg , Heidelberg, Germany .|2 Translational Lung Research Center Heidelberg (TLRC-H), German Center for Lung Research (DZL) , Heidelberg, Germany .
authors.forename: Heimo
authors.initials: H
authors.lastname: Mairbäurl
mesh_terms: D000328:Adult; D000531:Altitude; D000532:Altitude Sickness / Q000503:physiopathology*; D001794:Blood Pressure; D001992:Bronchoalveolar Lavage Fluid; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D011650:Pulmonary Alveoli / Q000378:metabolism*; D065589:Respiratory Tract Absorption / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D014661:Vasoconstriction
chemical_list: D012964:Sodium
keywords: Cl-transport; Na-transport; high altitude pulmonary edema; hypoxic pulmonary vasoconstriction; nasal potential difference