title: Heterogeneity of brainstem blood flow response to hypoxia in the anesthetized rat.
abstract: Cerebral blood flow is strictly regulated during hypoxic stress. Because of the preponderant role of the brainstem in cardiorespiratory controls, blood flow response to hypoxia is stronger in this region than in the cortex. However, the brainstem is made up of various regions which differ in their responsiveness to chemical stimuli. The objective of this study was to evaluate the distribution of blood flow during hypoxia using microsphere deposition methods in three brainstem regions containing key structures in cardiorespiratory controls: the nucleus tractus solitarus (NTS), the ventral respiratory groups (VRG) and the pontine respiratory groups (PRG). Microsphere injections were made during normoxia (FIO2=0.21) and after 15 min of hypoxia (FIO2=0.21). Based on this index, blood flow increase during hypoxia was higher in the VRG than in the dorsal part of the brainstem, containing the NTS and the PRG (P=0.002, n=10). These results suggest that blood flow response to hypoxia favours O(2) delivery in brainstem regions involved in respiratory rhythm generation.
authors.affiliation: Unité de Périnatalogie, Hôpital St-François d'Assie, Université Laval, Québec, Que., Canada G1L 3L5. gaspard.montandon.1@ulaval.ca
authors.forename: Gaspard
authors.initials: G
authors.lastname: Montandon
authors.forename: Richard
authors.initials: R
authors.lastname: Kinkead
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Lomenech
authors.forename: Aïda
authors.initials: A
authors.lastname: Bairam
authors.forename: Hervé
authors.initials: H
authors.lastname: Guénard
mesh_terms: D000758:Anesthesia; D000818:Animals; D001933:Brain Stem / Q000098:blood supply*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D000860:Hypoxia / Q000503:physiopathology*; D008863:Microspheres; D051381:Rats; D017208:Rats, Wistar; D012143:Respiratory Physiological Phenomena