title: Intra-individual variability in cerebrovascular and respiratory chemosensitivity: Can we characterize a chemoreflex "reactivity profile"?
abstract: Intra-individual variability in the magnitude of human cerebrovascular and respiratory chemoreflex responses is largely unexplored. By comparing response magnitudes of cerebrovascular CO2reactivity (CVR; middle and posterior cerebral arteries; MCA, PCA), central (CCR; CO2) and peripheral respiratory chemoreflexes (PCR; CO2and O2), we tested the hypothesis that a within-individual reactivity magnitude profile could be characterized. The magnitudes of CVR and CCR were tested with hyperoxic rebreathing and PCR magnitudes were tested through transient respiratory tests (TT-CO2, hypercapnia; TT-N2, hypoxia). No significant intra-individual relationships were found between CCR vs. CVR (MCA and PCA), CCR vs. PCR (TT-N2or TT-CO2) (r<0.2, P>0.3) response magnitudes. Statistically significant relationships were found between MCA vs. PCA reactivity (r=0.45, P<0.01) and PCR TT-N2vs. PCR TT-CO2(r=0.79, P<0.001) responses. Using qualitative and quantitative comparisons, we conclude that an intra-individual chemoreflex reactivity magnitude profile cannot be characterized. These data highlight the considerable between- and within-individual variability that exists in human cerebrovascular and respiratory chemoreflexes.
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6.
authors.forename: Kennedy J
authors.initials: KJ
authors.lastname: Borle
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6.
authors.forename: Jamie R
authors.initials: JR
authors.lastname: Pfoh
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6; School of Health and Exercise Science, University of British Columbia, 3333 University Way, Kelowna, BC, Canada V1V 1V7.
authors.forename: Lindsey M
authors.initials: LM
authors.lastname: Boulet
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6.
authors.forename: Maria
authors.initials: M
authors.lastname: Abrosimova
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6; School of Health and Exercise Science, University of British Columbia, 3333 University Way, Kelowna, BC, Canada V1V 1V7.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Tymko
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6; Faculty of Physical Education and Recreation, University of Alberta, 116 St & 85 Ave, Edmonton, AB, Canada T6G 2R3.
authors.forename: Rachel J
authors.initials: RJ
authors.lastname: Skow
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6.
authors.forename: Amy
authors.initials: A
authors.lastname: Varner
authors.affiliation: Department of Biology, Faculty of Science and Technology, Mount Royal University, 4825 Mount Royal Gate SW, Calgary, AB, Canada T3E 6K6. Electronic address: tday@mtroyal.ca.
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Day
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000378:metabolism*; D002536:Cerebral Arteries / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002628:Chemoreceptor Cells / Q000502:physiology; D005260:Female; D006801:Humans; D018496:Hyperoxia / Q000378:metabolism; D008297:Male; D010100:Oxygen / Q000378:metabolism; D012018:Reflex / Q000502:physiology*; D012119:Respiration
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: Central respiratory chemoreflex; Cerebrovascular reactivity; Inter-individual variability; Intra-individual variability; Peripheral respiratory chemoreflex