Hypoxia is not the primary mechanism contributing to exercise-induced proteinuria

Joyce, Kelsey E., Delamere, John, Bradwell, Susie B., Myers, Stephen D., Ashdown, Kimberley, Rue, Carla Amanda, Lucas, Samuel J. E., Thomas, Owen D., Fountain, Amy, Edsell, Mark R., Myers, Fiona, Malein, Will, Imray, Chris, Clarke, Alex, Lewis, Christopher T., Newman, Charles, Johnson, Brian, Cadigan, Patrick, Wright, Alexander and Bradwell, Arthur (2020) Hypoxia is not the primary mechanism contributing to exercise-induced proteinuria. BMJ Open Sport & Exercise Medicine, 6 (1). ISSN 2055-7647

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Abstract

Introduction
Proteinuria increases at altitude and with
exercise, potentially as a result of hypoxia. Using urinary
alpha-1 acid glycoprotein (α1-AGP) levels as a sensitive
marker of proteinuria, we examined the impact of relative
hypoxia due to high altitude and blood pressure-lowering
medication on post-exercise proteinuria.

Methods
Twenty individuals were pair-matched for sex,
age and ACE genotype. They completed maximal exercise
tests once at sea level and twice at altitude (5035 m).
Losartan (100 mg/day; angiotensin-receptor blocker) and
placebo were randomly assigned within each pair 21
days before ascent. The first altitude exercise test was
completed within 24–48 hours of arrival (each pair within
~1 hour). Acetazolamide (125mg two times per day) was
administrated immediately after this test for 48 hours until
the second altitude exercise test.

Results
With placebo, post-exercise α1-AGP levels
were similar at sea level and altitude. Odds ratio (OR) for
increased resting α1-AGP at altitude versus sea level was
greater without losartan (2.16 times greater). At altitude,
OR for reduced post-exercise α1-AGP (58% lower) was
higher with losartan than placebo (2.25 times greater,
p=0.059) despite similar pulse oximetry (SpO2
) (p=0.95)
between groups. Acetazolamide reduced post-exercise
proteinuria by approximately threefold (9.3±9.7 vs 3.6±6.0
μg/min; p=0.025) although changes were not correlated
(r=−0.10) with significant improvements in SpO2
(69.1%±4.5% vs 75.8%±3.8%; p=0.001).

Discussion
Profound systemic hypoxia imposed by
altitude does not result in greater post-exercise proteinuria
than sea level. Losartan and acetazolamide may attenuate
post-exercise proteinuria, however further research is
warranted.

Item Type: Article
Subjects: Q Science > QP Physiology
R Medicine > R Medicine (General) > R735 Medical education. Medical schools. Research
Divisions: Departments > Sport and Exercise Sciences
Related URLs:
Depositing User: Stephen Myers
Date Deposited: 08 Apr 2020 11:51
Last Modified: 12 May 2020 09:54
URI: http://eprints.chi.ac.uk/id/eprint/5122

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