Trans-cerebral HCO3− and PCO2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans
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Trans-cerebral HCO3− and PCO2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans. / Caldwell, Hannah Grace; Hoiland, Ryan L; Smith, Kurt J; Brassard, Patrice; Bain, Anthony R; Tymko, Michael M.; Howe, Connor A; Carr, Jay M J R; Stacey, Benjamin S; Bailey, Damian M; Drapeau, Audrey; Sekhon, Mypinder S; MacLeod, David B; Ainslie, Philip N.
In: Journal of Cerebral Blood Flow and Metabolism, Vol. 42, No. 4, 2022, p. 559-571.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Trans-cerebral HCO3− and PCO2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans
AU - Caldwell, Hannah Grace
AU - Hoiland, Ryan L
AU - Smith, Kurt J
AU - Brassard, Patrice
AU - Bain, Anthony R
AU - Tymko, Michael M.
AU - Howe, Connor A
AU - Carr, Jay M J R
AU - Stacey, Benjamin S
AU - Bailey, Damian M
AU - Drapeau, Audrey
AU - Sekhon, Mypinder S
AU - MacLeod, David B
AU - Ainslie, Philip N
N1 - Publisher Copyright: © The Author(s) 2021.
PY - 2022
Y1 - 2022
N2 - 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).
AB - 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).
KW - Acidosis
KW - Bicarbonate
KW - Carbon dioxide
KW - Exercise
KW - Trans-cerebral exchange
U2 - 10.1177/0271678X211065924
DO - 10.1177/0271678X211065924
M3 - Journal article
C2 - 34904461
AN - SCOPUS:85120355584
VL - 42
SP - 559
EP - 571
JO - Journal of Cerebral Blood Flow and Metabolism
JF - Journal of Cerebral Blood Flow and Metabolism
SN - 0271-678X
IS - 4
ER -
ID: 306186439