title: Morphine has latent deleterious effects on the ventilatory responses to a hypoxic challenge.
abstract: The aim of this study was to determine whether morphine depresses the ventilatory responses elicited by a hypoxic challenge (10% O2, 90% N2) in conscious rats at a time when the effects of morphine on arterial blood gas (ABG) chemistry, Alveolar-arterial (A-a) gradient and minute ventilation (VM) had completely subsided. In vehicle-treated rats, each episode of hypoxia stimulated ventilatory function and the responses generally subsided during each normoxic period. Morphine (5 mg/kg, i.v.) induced an array of depressant effects on ABG chemistry, A-a gradient and VM(via decreases in tidal volume). Despite resolution of these morphine-induced effects, the first episode of hypoxia elicited substantially smaller increases in VMthan in vehicle-treated rats, due mainly to smaller increases in frequency of breathing. The pattern of ventilatory responses during subsequent episodes of hypoxia and normoxia changed substantially in morphine-treated rats. It is evident that morphine has latent deleterious effects on ventilatory responses elicited by hypoxic challenge.
authors.affiliation: Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
authors.forename: Walter J
authors.initials: WJ
authors.lastname: May
authors.affiliation: Division of Biology, Galleon Pharmaceuticals, Horsham, PA 19044, USA.
authors.forename: Ryan B
authors.initials: RB
authors.lastname: Gruber
authors.affiliation: Division of Biology, Galleon Pharmaceuticals, Horsham, PA 19044, USA.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Discala
authors.affiliation: Division of Biology, Galleon Pharmaceuticals, Horsham, PA 19044, USA.
authors.forename: Veljko
authors.initials: V
authors.lastname: Puskovic
authors.affiliation: Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
authors.forename: Fraser
authors.initials: F
authors.lastname: Henderson
authors.affiliation: Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Palmer
authors.affiliation: Pediatric Respiratory Medicine, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Lewis
keywords: arterial blood gas chemistry; conscious rats; hypoxia; minute ventilation; morphine