title: Time-course and reversibility of the hypoxia-induced alterations in cerebral vascularity and cerebral capillary glucose transporter density.
abstract: The adult rat adapts to prolonged moderate hypobaric hypoxia by polycythemia, increased brain vascularity, and increased density of the brain capillary glucose transporter (GLUT-1). We now report on the time-course and reversibility of these adaptive alterations. Adult male Wistar rats were subjected to hypobaric hypoxia at 0.5 atmosphere for periods of 4 days or 1, 2 or 3 weeks, and compared to normoxic littermate controls. Reversibility of the effects of hypoxia was studied in rats subjected to hypobaric hypoxia for 3 weeks and then allowed to recover at normobaric conditions for 3 additional weeks. Cerebral vascularity was studied in cross-sections of the cerebral cortex that were immunocytochemically stained with a GLUT-1 antibody. The density of GLUT-1 was determined in isolated cerebral microvessels by quantitative autoradiography of immunoblots. Blood hematocrit and cerebral microvascularity did not significantly increase after 4 days of hypoxia, but were significantly increased at 1, 2 and 3 weeks of hypoxia. Three weeks of normoxic recovery after 3 weeks of hypoxia reversed the polycythemia and cerebral hypervascularity. However, the density of GLUT-1 in isolated cerebral microvessels, which was significantly increased after 1 and 3 weeks of hypoxia, remained elevated after 3 weeks of normoxia.
authors.affiliation: Department of Neurology, Case Western Reserve University School of Medicine, Cleveland, OH, USA.
authors.forename: N
authors.initials: N
authors.lastname: Harik
authors.forename: S I
authors.initials: SI
authors.lastname: Harik
authors.forename: N T
authors.initials: NT
authors.lastname: Kuo
authors.forename: K
authors.initials: K
authors.lastname: Sakai
authors.forename: R J
authors.initials: RJ
authors.lastname: Przybylski
authors.forename: J C
authors.initials: JC
authors.lastname: LaManna
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D001835:Body Weight; D001921:Brain / Q000098:blood supply* / Q000503:physiopathology; D002196:Capillaries / Q000737:chemistry; D051272:Glucose Transporter Type 1; D000860:Hypoxia / Q000503:physiopathology*; D002534:Hypoxia, Brain / Q000503:physiopathology*; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; C495679:Slc2a1 protein, rat