The Effect of Hypercapnia on Cortical Metabolic Rate and Mitochondrial Redox Status

Mada Hashem; Ying Wu; Jeff F Dunn

doi:10.1007/978-3-031-42003-0_3

The Effect of Hypercapnia on Cortical Metabolic Rate and Mitochondrial Redox Status

Adv Exp Med Biol. 2023:1438:15-20. doi: 10.1007/978-3-031-42003-0_3.

Authors

Mada Hashem^{1

2

3}, Ying Wu^{4

5

6}, Jeff F Dunn^{4

5

6}

Affiliations

¹ Department of Radiology, University of Calgary, Calgary, AB, Canada. mada.hashem@ucalgary.ca.
² Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada. mada.hashem@ucalgary.ca.
³ Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada. mada.hashem@ucalgary.ca.
⁴ Department of Radiology, University of Calgary, Calgary, AB, Canada.
⁵ Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
⁶ Experimental Imaging Centre, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.

PMID: 37845433
DOI: 10.1007/978-3-031-42003-0_3

Abstract

Hypercapnia is commonly used as a vasodilatory stimulus in both basic and clinical research. There have been conflicting reports about whether cerebral metabolic rate of oxygen (CMRO₂) is maintained at normal levels during increases of cerebral blood flow (CBF) and oxygen delivery caused by hypercapnia.This study aims to provide insight into how hypercapnia may impact CMRO₂ and brain mitochondrial function. We introduce data from mouse cortex collected with a novel multimodality system which combines MRI and near-infrared spectroscopy (NIRS). We quantify CBF, tissue oxygen saturation (S_tO₂), oxidation state of the mitochondrial enzyme cytochrome c oxidase (CCO), and CMRO₂.During hypercapnia, CMRO₂ did not change while CBF, S_tO₂, and the oxidation state of CCO increased significantly. This paper supports the conclusion that hypercapnia does not change CMRO₂. It also introduces the application of a multimodal NIRS-MRI system which enables non-invasive quantification of CMRO₂, and other physiological variables, in the cerebral cortex of mouse models.

Keywords: Cortical metabolic rate; Hypercapnia; Mitochondrial redox status.

MeSH terms

Animals
Brain / metabolism
Cerebral Cortex / metabolism
Cerebrovascular Circulation / physiology
Hypercapnia*
Magnetic Resonance Imaging / methods
Mice
Oxygen Consumption / physiology
Oxygen* / metabolism

Substances

Oxygen