Superoxide dismutase and cytochrome oxidase in collapsed lungs: possible role in reexpansion edema.
This study examined the effects of lung collapse, a condition that causes relative hypoxia in lung tissues, on superoxide dismutase (SOD), cytochrome oxidase (cyt ox), and pyruvate kinase (py ki) activities in rabbits. Cyanide-insensitive respiration measurements were done in collapsed and contralateral lungs, as an index of intracellular free radical production. Rabbits' right lungs were collapsed for 7 days after which the animals were killed. We found that control rabbit lungs contained approximately 25 SOD units/mg DNA measured with 10(-5) M KCN (total SOD) and approximately 11 SOD units/mg DNA measured with 10(-3) M KCN (mitochondrial or MnSOD). Right lung collapse caused a 25% decrease in mitochondrial SOD activity after 7 days (P less than 0.05), whereas no significant changes occurred in right or left lungs' total SOD activity. In control rabbits cyt ox activity averaged approximately 0.009 mumol ferrocytochrome c.min-1.mg DNA-1. Right lung collapse caused a greater than 40% decrease in cyt ox activity after 7 days of collapse (P less than 0.05), whereas cyt ox activity in contralateral left lungs did not change. Pyruvate kinase activity, a marker for anaerobic glycolysis resulting from tissue hypoxia, increased 49% in collapsed right lungs (P less than 0.01). Cyanide-insensitive respiration was 83% higher in 7 day-collapsed lungs (2.28 +/- 0.66 microliters O2.min-1.g-1) compared with contralateral lungs (1.24 +/- 0.34, P less than 0.05), indicating increased O2-. and H2O2 production in this tissue after homogenization at normoxic PO2 (approximately 150 Torr).(ABSTRACT TRUNCATED AT 250 WORDS)
Jackson
R M
RM
Birmingham Veterans Administration Medical Center 35233.
Brannen
A L
AL
Veal
C F
CF
Fulmer
J D
JD
D000818:Animals; D003486:Cyanides / Q000494:pharmacology; D004247:DNA / Q000032:analysis; D003576:Electron Transport Complex IV / Q000378:metabolism*; D008168:Lung / Q000201:enzymology*; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D011654:Pulmonary Edema / Q000201:enzymology*; D011770:Pyruvate Kinase / Q000378:metabolism; D011817:Rabbits; D012119:Respiration / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism*
D003486:Cyanides; D004247:DNA; D013482:Superoxide Dismutase; D003576:Electron Transport Complex IV; D011770:Pyruvate Kinase