Trans-cerebral HCO3- and PCO2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans.

Journal Article (Journal Article)

This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO3-]) and carbon dioxide tension (PCO2) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO2 (PaCO2) (n = 39); and 2) metabolic acidosis via incremental cycling exercise to exhaustion (n = 24). During respiratory acidosis, arterial [HCO3-] increased by 0.15 ± 0.05 mmol ⋅ l-1 per mmHg elevation in PaCO2 across a wide physiological range (35 to 60 mmHg PaCO2; P < 0.001). The narrowing of the venous-arterial [HCO3-] and PCO2 differences with respiratory acidosis were both related to the hypercapnia-induced elevations in cerebral blood flow (CBF) (both P < 0.001; subset n = 27); thus, trans-cerebral [HCO3-] exchange (CBF × venous-arterial [HCO3-] difference) was reduced indicating a shift from net release toward net uptake of [HCO3-] (P = 0.004). Arterial [HCO3-] was reduced by -0.48 ± 0.15 mmol ⋅ l-1 per nmol ⋅ l-1 increase in arterial [H+] with exercise-induced acidosis (P < 0.001). There was no relationship between the venous-arterial [HCO3-] difference and arterial [H+] with exercise-induced acidosis or CBF; therefore, trans-cerebral [HCO3-] exchange was unaltered throughout exercise when indexed against arterial [H+] or pH (P = 0.933 and P = 0.896, respectively). These results indicate that increases and decreases in systemic [HCO3-] - during acute respiratory/exercise-induced metabolic acidosis, respectively - differentially affect cerebrovascular acid-base balance (via trans-cerebral [HCO3-] exchange).

Full Text

Duke Authors

Cited Authors

  • Caldwell, HG; Hoiland, RL; Smith, KJ; Brassard, P; Bain, AR; Tymko, MM; Howe, CA; Carr, JM; Stacey, BS; Bailey, DM; Drapeau, A; Sekhon, MS; MacLeod, DB; Ainslie, PN

Published Date

  • April 2022

Published In

Volume / Issue

  • 42 / 4

Start / End Page

  • 559 - 571

PubMed ID

  • 34904461

Pubmed Central ID

  • PMC8943603

Electronic International Standard Serial Number (EISSN)

  • 1559-7016

Digital Object Identifier (DOI)

  • 10.1177/0271678X211065924


  • eng

Conference Location

  • United States