title: Evidence against an increase in capillary permeability in subjects exposed to high altitude.
abstract: A potential pathogenetic cofactor for the development of acute mountain sickness and high-altitude pulmonary edema is an increase in capillary permeability, which could occur as a result of an inflammatory reaction and/or free radical-mediated injury to the lung. We measured the systemic albumin escape by intravenously injecting 5 muCi of 125I-labeled albumin and the plasma concentrations of cytokines, F2-isoprostanes (products of lipid peroxidation), and acute-phase proteins in 24 subjects exposed to 4,559 m. Ten subjects developed acute mountain sickness, and four subjects developed high-altitude pulmonary edema. The transcapillary escape rate of albumin was 6.9 +/- 2.0%/h (SD) at low (550 m) and 6.3 +/- 1.9%/h at high (4,559 m) altitude (P = 0.23; n = 24). The subjects with high-altitude pulmonary edema had a modest but insignificant increase in the transcapillary escape rate of albumin (4.6 +/- 1.9%/h at low vs. 5.7 +/- 1.9%/h at high altitude; P = 0.42; n = 4). Plasma concentrations of fibrinogen, alpha 1-acid glycoprotein, C-reactive protein, and interleukin-6 were unchanged in the early phases and significantly increased by the end of the observation period in the subjects with high-altitude pulmonary edema, whereas tumor necrosis factor-alpha and F2-isoprostanes did not change at all. This suggests that the inflammatory reaction was rather a consequence than a causative factor of high-altitude pulmonary edema. In summary, these data argue against a dominant role for increased systemic capillary permeability in the development of acute mountain sickness and high-altitude pulmonary edema.
authors.affiliation: Department of Medicine and Radiology, University of Bern, Inselspital, Switzerland.
authors.forename: G R
authors.initials: GR
authors.lastname: Kleger
authors.forename: P
authors.initials: P
authors.lastname: Bärtsch
authors.forename: P
authors.initials: P
authors.lastname: Vock
authors.forename: B
authors.initials: B
authors.lastname: Heilig
authors.forename: L J
authors.initials: LJ
authors.lastname: Roberts
authors.forename: P E
authors.initials: PE
authors.lastname: Ballmer
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000209:Acute-Phase Proteins / Q000378:metabolism; D000531:Altitude; D002199:Capillary Permeability / Q000502:physiology*; D016207:Cytokines / Q000097:blood; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D011460:Prostaglandins F / Q000097:blood; D011654:Pulmonary Edema / Q000503:physiopathology
chemical_list: D000209:Acute-Phase Proteins; D016207:Cytokines; D005609:Free Radicals; D011460:Prostaglandins F