Time course and magnitude of ventilatory and renal acid-base acclimatization following rapid ascent to and residence at 3,800 m over nine days

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dc.contributor.authorBird, Jordan D.
dc.contributor.authorLeacy, Jack K.
dc.contributor.authorFoster, Glen Edward
dc.contributor.authorRickards, Caroline A.
dc.contributor.authorWilson, Richard J. A.
dc.contributor.authorO'Halloran, Ken D.
dc.contributor.authorJendzjowsky, Nicholas G.
dc.contributor.authorPentz, Brandon A.
dc.contributor.authorByman, Britta R. M.
dc.contributor.authorThrall, Scott F.
dc.contributor.authorSkalk, Alexandra L.
dc.contributor.authorHewitt, Sarah A.
dc.contributor.authorSteinback, Craig D.
dc.contributor.authorBurns, David
dc.contributor.authorOndrus, Peter
dc.contributor.authorDay, Trevor A.
dc.contributor.funderUniversity College Corken
dc.contributor.funderGovernment of Albertaen
dc.contributor.funderNatural Sciences and Engineering Research Council of Canadaen
dc.contributor.funderMichael Smith Foundation for Health Researchen
dc.contributor.funderHeart and Stroke Foundation of Canadaen
dc.contributor.funderFrancis Family Foundationen
dc.contributor.funderAmerican Heart Associationen
dc.contributor.funderUniversity of Calgaryen
dc.date.accessioned2021-05-10T08:47:40Z
dc.date.available2021-05-10T08:47:40Z
dc.date.issued2021-03-11
dc.date.updated2021-03-24T10:00:47Z
dc.description.abstractRapid ascent to high altitude imposes an acute hypoxic and acid-base challenge, with ventilatory and renal acclimatization countering these perturbations. Specifically, ventilatory acclimatization improves oxygenation, but with concomitant hypocapnia and respiratory alkalosis. A compensatory, renally-mediated relative metabolic acidosis follows via bicarbonate elimination, normalizing arterial pH(a). The time-course and magnitude of these integrated acclimatization processes are highly variable between individuals. Using a previously-developed metric of renal reactivity (RR), indexing the change in arterial bicarbonate concentration (∆[HCO3-]a; renal response) over the change in arterial pressure of CO2 (∆PaCO2; renal stimulus), we aimed to characterize changes in RR magnitude following rapid ascent and residence at altitude. Resident lowlanders (n=16) were tested at 1,045 m (Day [D]0) prior to ascent, on D2 within 24-hours of arrival, and D9 during residence at 3,800 m. Radial artery blood draws were obtained to measure acid-base variables: PaCO2, [HCO3-]a and pHa. Compared to D0, PaCO2 and [HCO3-]a were lower on D2 (P<0.01) and D9 (P<0.01), whereas significant changes in pHa (P>0.058) and RR (P=0.056) were not detected. As pHa appeared fully compensated on D2 and RR did not increase significantly from D2 to D9, these data demonstrate renal acid-base compensation within 24-hours at moderate steady-state altitude. Moreover, RR was strongly and inversely correlated with ∆pHa on D2 and D9 (r≤-0.95; P<0.0001), suggesting that a high-gain renal response better protects pHa. Our study highlights the differential time-course, magnitude, and variability of integrated ventilatory and renal acid-base acclimatization following rapid ascent and residence at high altitude.en
dc.description.sponsorshipGovernment of Alberta (Student Temporary Employment Program); Natural Sciences and Engineering Research Council of Canada (Undergraduate Student Research Assistantships; BRAIN CREATE Program; Discovery grants CDS RGPIN 06637; TAD, RGPIN 04915; RJAW RGPIN-03941); Michael Smith Foundation for Health Research (Research Scholarship); Heart and Stroke Foundation of Canada (Joint National and Alberta New Investigator Award HSFC NNIA Steinback); Francis Family Foundation (Post-Doctoral Fellowship); American Heart Association (Grant-in-Aid 17GRNT33671110); University of Calgary (URGC grant)en
dc.description.statusPeer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationBird, J. D., Leacy, J. K., Foster, G. E., Rickards, C. A., Wilson, R. J. A., O'Halloran, K. D., Jendzjowsky, N. G., Pentz, B. A., Byman, B. R. M., Thrall, S. F., Skalk, A. L., Hewitt, S. A., Steinback, C. D., Burns, D., Ondrus, P. and Day, T. A. (2021) 'Time course and magnitude of ventilatory and renal acid-base acclimatization following rapid ascent to and residence at 3,800 m over nine days', Journal of Applied Physiology. doi: 10.1152/japplphysiol.00973.2020en
dc.identifier.doi10.1152/japplphysiol.00973.2020en
dc.identifier.eissn1522-1601
dc.identifier.issn8750-7587
dc.identifier.journaltitleJournal of Applied Physiologyen
dc.identifier.urihttps://hdl.handle.net/10468/11260
dc.language.isoenen
dc.publisherAmerican Physiological Societyen
dc.rights© 2021, Journal of Applied Physiology. All rights reserved.en
dc.subjectHigh altitudeen
dc.subjectHypoxiaen
dc.subjectVentilatory acclimatizationen
dc.subjectAcid-baseen
dc.subjectRenal compensationen
dc.titleTime course and magnitude of ventilatory and renal acid-base acclimatization following rapid ascent to and residence at 3,800 m over nine daysen
dc.typeArticle (peer-reviewed)en
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