title: Role of adenosine in the hypoxic ventilatory response of the newborn piglet.
abstract: The role of intracerebral adenosine levels in the control of ventilatory response to hypoxia was explored in 15 spontaneously breathing intubated piglets, 1-5 days old, sedated with chloral hydrate. Respiration was recorded via by a pneumotachograph. In all animals exposed to hypoxia (12% O2) for 10 minutes. There was an initial increase in ventilation followed by a late decrease (the biphasic ventilatory response). Both intravenous caffeine citrate (20 mg/kg) and an FiCO2 of 0.05 separately abolished or attenuated the late ventilatory depression associated with hypoxia. In the same piglets, the administration of 10 micrograms dipyridamole, a competitive inhibitor of adenosine receptors, directly into the cerebral ventricles abolished the hyperventilatory response to hypoxia. Conversely, the use of 20 micrograms intraventricular 8-phenyltheophylline abolished the late ventilatory depression associated with hypoxia. Neither drug had a direct effect on ventilation at the time of injection. These results suggest that adenosine is a part of the diphasic ventilatory response to hypoxia.
authors.affiliation: Division of Developmental Pharmacology, McGill University-Montreal Children's Hospital, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Lopes
authors.forename: G M
authors.initials: GM
authors.lastname: Davis
authors.forename: K
authors.initials: K
authors.lastname: Mullahoo
authors.forename: J V
authors.initials: JV
authors.lastname: Aranda
mesh_terms: D000241:Adenosine / Q000037:antagonists & inhibitors / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D002110:Caffeine / Q000494:pharmacology; D002555:Cerebrospinal Fluid / Q000737:chemistry; D002951:Citrates / Q000494:pharmacology; D004176:Dipyridamole / Q000494:pharmacology; D004338:Drug Combinations; D000860:Hypoxia / Q000503:physiopathology*; D010100:Oxygen / Q000502:physiology; D058915:Purinergic P1 Receptor Antagonists; D012119:Respiration / Q000502:physiology*; D013552:Swine; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D002951:Citrates; D004338:Drug Combinations; D058915:Purinergic P1 Receptor Antagonists; D002110:Caffeine; D004176:Dipyridamole; D013806:Theophylline; C028322:8-phenyltheophylline; D000241:Adenosine; D010100:Oxygen; C026189:caffeine citrate