title: Effect of body position on ventilatory responses in anaesthetised mice.
abstract: The effects of body position on ventilatory responses to chemical stimuli have rarely been studied in experimental animals, despite evidence that position may be a factor in respiratory results. The purpose of this study was to test whether body position could affect acute ventilatory responses to 4-min periods of moderate hypercapnia (5% CO(2) in O(2)) and poikilocapnic hypoxia (15% O(2) in N(2)) in the urethane-anaesthetised mouse. Respiratory measurements were conducted with mice in the prone and supine positions with a whole-body, single-chamber plethysmograph. During hypoxia, the time course of minute ventilation (V (E)) was similar in the two positions, but the breathing pattern was different. After the response peak, V (E) depended on respiratory frequency (f) and tidal volume (V(T)) in the prone position but mainly on V(T) in the supine position. In the supine position, f declined below the baseline values toward the end of hypoxic exposure. During hypercapnia, there were no ventilatory differences between the prone and supine positions. Brief hypoxic exposure elicited f depression in the supine position in the anaesthetised mouse. The depressive effect on f suggests that the supine position may not be optimal for sustaining ventilation, particularly during hypoxia.
authors.affiliation: Department of Physiology, Showa University School of Medicine, Shinagawa-ku, Tokyo, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Izumizaki
authors.forename: Mieczyslaw
authors.initials: M
authors.lastname: Pokorski
authors.forename: Yohei
authors.initials: Y
authors.lastname: Ishihara
authors.forename: Michiko
authors.initials: M
authors.lastname: Iwase
authors.forename: Ikuo
authors.initials: I
authors.lastname: Homma
mesh_terms: D000758:Anesthesia; D000818:Animals; D001784:Blood Gas Analysis; D006935:Hypercapnia / Q000503:physiopathology; D000860:Hypoxia / Q000503:physiopathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016684:Prone Position / Q000502:physiology*; D012123:Pulmonary Ventilation; D016683:Supine Position / Q000502:physiology*