title: Oxidative stress and matrix metalloproteinase-9 activity in the liver after hypoxia and reoxygenation with 21% or 100% oxygen in newborn piglets.
abstract: We designed a randomized controlled study to identify and compare the liver tissue responses in systemic hypoxia and resuscitation with 21% and 100% oxygen using an animal model of neonatal hypoxia and reoxygenation. Twenty-seven piglets (1-3 days old, weight 1.5-2.0 kg) were acutely instrumented and mechanically ventilated. The animals underwent 2 h of normocapnic alveolar hypoxia (10-15% oxygen) then reoxygenation with 21% or 100% oxygen for 1 h, then 1 h with 21% oxygen. Controls were sham-operated without hypoxia-reoxygenation. After 2 h of reoxygenation liver tissue samples were immediately processed for histological and biochemical analyses of markers of oxidative stress and tissue injury. Two hours of hypoxia caused a significant reduction in mean arterial pressure with cardiogenic shock and metabolic acidemia, with similar recovery upon resuscitation with 21% and 100% oxygen. After 2 h of reoxygenation, the hepatic GSSG:total glutathione ratio and matrix metalloproteninase-9 activity, which correlated with the portal venous oxygenation at 15 min of reoxygenation, were greater in the 100% group and hepatic lactate level was higher in the 21% group than the controls (all P<0.05). Both hypoxic-reoxygenated groups had similarly elevated hepatic Bcl-2 levels. Apart from more non-distinct mitochondria identified in the 100% group, hepatic tissue adenylate energy charge and plasma transaminases levels did not differ among groups. We concluded that in this acute model of neonatal hypoxia and reoxygenation, resuscitation using 21% oxygen avoids the excess oxidative stress and elevated matrix metalloproteninase-9 activity in the liver when 100% oxygen was used. The study supports the conservative use of oxygen in optimizing post-hypoxic hepatic recovery.
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, AB, Canada.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Stevens
authors.forename: Thomas
authors.initials: T
authors.lastname: Churchill
authors.forename: Karien
authors.initials: K
authors.lastname: Fokkelman
authors.forename: Erika
authors.initials: E
authors.lastname: Haase
authors.forename: Halliday
authors.initials: H
authors.lastname: Idikio
authors.forename: Gregory
authors.initials: G
authors.lastname: Korbutt
authors.forename: David L
authors.initials: DL
authors.lastname: Bigam
authors.forename: Po-Yin
authors.initials: PY
authors.lastname: Cheung
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D000831:Animals, Newborn; D001219:Aspartate Aminotransferases / Q000097:blood; D005260:Female; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D000860:Hypoxia / Q000097:blood / Q000503:physiopathology*; D019344:Lactic Acid / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008297:Male; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D010100:Oxygen / Q000097:blood / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011897:Random Allocation; D013552:Swine; D013997:Time Factors; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D019344:Lactic Acid; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D005978:Glutathione; D010100:Oxygen; D019803:Glutathione Disulfide