title: Influence of adenosine on cerebral blood flow during hypoxic hypoxia in the newborn piglet.
abstract: This study investigated the role of adenosine in the regulation of neonatal cerebral blood flow (CBF) during moderate (arterial PO2 = 47 +/- 9 Torr) and severe (arterial PO2 = 25 +/- 4 Torr) hypoxia. Twenty-eight anesthetized and ventilated newborn piglets were assigned to four groups: 8 were injected intravenously with the vehicle (controls, group 1); 13 received an intravenous injection of 8-phenyltheophylline (8-PT), a potent adenosine receptor blocker, either 4 mg/kg (group 2, n = 6, mean cerebrospinal fluid (CSF) levels less than 1 mg/l) or 8 mg/kg (group 3, n = 7, mean CSF levels less than 3.5 mg/l); and 7 received an intracerebroventricular injection of 10 micrograms 8-PT (group 4). During normoxia, CBF was not altered by vehicle or 8-PT injections. In group 1, 10 min of moderate and severe hypoxia increased total CBF by 112 +/- 36 and 176 +/- 28% (SE), respectively. Compared with controls, the cerebral hyperemia during moderate hypoxia was not altered in group 2, attenuated in group 3 (to 53 +/- 13%, P = NS), and completely blocked in group 4 (P less than 0.01). CBF increase secondary to severe hypoxia was attenuated only in group 4 (74 +/- 29%, P less than 0.05). CSF concentrations of adenosine and adenosine metabolites measured by high-performance liquid chromatography increased during hypoxia. Arterial O2 content was inversely correlated (P less than 0.005) to maximal CSF levels of adenosine (r = 0.73), inosine (r = 0.87), and hypoxanthine (r = 0.80).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Developmental Pharmacology and Perinatal Research Unit, McGill University, Montreal, Quebec, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Laudignon
authors.forename: E
authors.initials: E
authors.lastname: Farri
authors.forename: K
authors.initials: K
authors.lastname: Beharry
authors.forename: J
authors.initials: J
authors.lastname: Rex
authors.forename: J V
authors.initials: JV
authors.lastname: Aranda
mesh_terms: D000241:Adenosine / Q000037:antagonists & inhibitors / Q000134:cerebrospinal fluid / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001158:Arteries; D002560:Cerebrovascular Circulation / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000134:cerebrospinal fluid; D000860:Hypoxia / Q000503:physiopathology*; D007276:Injections, Intraventricular; D007288:Inosine / Q000134:cerebrospinal fluid; D010100:Oxygen / Q000097:blood; D013552:Swine; D013806:Theophylline / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000134:cerebrospinal fluid / Q000494:pharmacology; D014655:Vascular Resistance
chemical_list: D007042:Hypoxanthines; D019271:Hypoxanthine; D007288:Inosine; D013806:Theophylline; C028322:8-phenyltheophylline; D000241:Adenosine; D010100:Oxygen