EPR spectroscopic evidence of iron-catalysed free radical formation in chronic mountain sickness: Dietary causes and vascular consequences.

Abstract

Chronic mountain sickness (CMS) is a high-altitude (HA) maladaptation syndrome characterised by elevated systemic oxidative-nitrosative stress (OXNOS) due to a free radical-mediated reduction in vascular nitric oxide (NO) bioavailability. To better define underlying mechanisms and vascular consequences, this study compared healthy male lowlanders (80 m, n = 10) against age/sex-matched highlanders born and bred in La Paz, Bolivia (3600 m) with (CMS+, n = 10) and without (CMS-, n = 10) CMS. Cephalic venous blood was assayed using electron paramagnetic resonance spectroscopy and reductive ozone-based chemiluminescence. Nutritional intake was assessed via dietary recall. Systemic vascular function and structure were assessed via flow-mediated dilatation, aortic pulse wave velocity and carotid intima-media thickness using duplex ultrasound and applanation tonometry. Basal systemic OXNOS was permanently elevated in highlanders (P = <0.001 vs. lowlanders) and further exaggerated in CMS+, reflected by increased hydroxyl radical spin adduct formation (P = <0.001 vs. CMS-) subsequent to liberation of free 'catalytic' iron consistent with a Fenton and/or nucleophilic addition mechanism(s). This was accompanied by elevated global protein carbonylation (P = 0.046 vs. CMS-) and corresponding reduction in plasma nitrite (P = <0.001 vs. lowlanders). Dietary intake of vitamins C and E, carotene, magnesium and retinol were lower in highlanders and especially deficient in CMS + due to reduced consumption of fruit and vegetables (P = <0.001 to 0.028 vs. lowlanders/CMS-). Systemic vascular function and structure were also impaired in highlanders (P = <0.001 to 0.040 vs. lowlanders) with more marked dysfunction observed in CMS+ (P = 0.035 to 0.043 vs. CMS-) in direct proportion to systemic OXNOS (r = -0.692 to 0.595, P = <0.001 to 0.045). Collectively, these findings suggest that lifelong exposure to iron-catalysed systemic OXNOS, compounded by a dietary deficiency of antioxidant micronutrients, likely contributes to the systemic vascular complications and increased morbidity/mortality in CMS+. TRIAL REGISTRY: ClinicalTrials.gov; No: NCT01182792; URL: www.clinicaltrials.gov.

• Authors: Damian M Bailey, Marcel Culcasi, Teresa Filipponi, Julien V Brugniaux, Benjamin S Stacey, Christopher J Marley, Rodrigo Soria, Stefano F Rimoldi, David Cerny, Emrush Rexhaj, Lorenza Pratali, Carlos Salinas Salmòn, Carla Murillo Jáuregui, Mercedes Villena, Francisco Villafuerte, Antal Rockenbauer, Sylvia Pietri, Urs Scherrer, Claudio Sartori
• Journal: Free radical biology & medicine (Free Radic Biol Med) Vol. 184 Pg. 99-113 (05 01 2022) ISSN: 1873-4596 [Electronic] United States
• PMID: 35398201 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.

Chemical References

• Free Radicals
• Iron

Topics

• Altitude
• Altitude Sickness (metabolism)
• Carotid Intima-Media Thickness
• Chronic Disease
• Electron Spin Resonance Spectroscopy
• Free Radicals
• Humans
• Iron
• Male
• Pulse Wave Analysis