title: Influence of altered O2 tension on substrate metabolism in perfused rat lung.
abstract: Effects of hypoxia (1.5 h) on glucose and palmitate metabolism were investigated in perfused lungs from normal rats and rats exposed for 24 h to hypobaric conditions (simulated altitude of 24,000 ft). Hypoxic lungs were ventilated with 5% O2-5% CO2 and control lungs with 21% O2-5% CO2. Blood gases and pH remained stable during the 1.5-h perfusion period. Exposure of normal rat lungs to 1.5 h of in vitro hypoxia (blood Po2=34 mmHg) significantly increased lactate production and mean arterial pulmonary pressure, but did not alter glucose uptake, pyruvate levels, and oxidation of either [U-14C]glucose or [1-14C]palmitate to CO2. Incorporation of labeled glucose and palmitate into lung lipids was also unaltered. In contrast to normal lungs, prior exposure to hypoxia for 24 h and subsequent perfusion under hypoxic conditions significantly stimulated glucose uptake (74% increase), markedly increased glucose incorporation into lung lipids, and increased oxidation of glucose to CO2. Lactate/pyruvate ratios also showed a significant 38% increase. Lung glycogen was unchanged following 24 h hypoxia. These data indicate that adaptive changes occur in metabolic processes within the lung during acute changes in O2 tension.
mesh_terms: D000818:Animals; D004780:Environment, Controlled; D005215:Fasting; D005947:Glucose / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D007773:Lactates / Q000378:metabolism; D050356:Lipid Metabolism; D008168:Lung / Q000378:metabolism*; D008297:Male; D010100:Oxygen; D010168:Palmitates / Q000378:metabolism*; D010169:Palmitic Acids / Q000378:metabolism*; D010477:Perfusion; D051381:Rats
chemical_list: D007773:Lactates; D010168:Palmitates; D010169:Palmitic Acids; D005947:Glucose; D010100:Oxygen