Metabolic response to carbon monoxide by isolated rat lungs

Glucose metabolism was studied in isolated rat lungs ventilated with 95% O2.5% CO2 (control), 95% N2: 5% CO2 (hypoxia), and 95% CO:5% CO2 (carbon monoxide) and perfused for 100-120 min with Krebs-Ringer-bicarbonate buffer, pH 7.4, containing [U-14C] and [3-3H]glucose. The production of 14C-labeled lactate plus pyruvate (L + P) and of 14CO2 represented 48% and 22% respectively, of the total [14C]glucose utilization. The lactate-to-pyruvate ratio (L/P) was 8.7. Tritium was recovered predominantly as 3H2O in the perfusate. Wth carbon monoxide ventilation, L + P production was increased by 357% with an L/P of 52.9, and 14CO2 production was markedly decreased. A 56% decrease in lung ATP content was associated with decreased incorporation of 14C into fatty acids. Compared with CO, changes with N2 ventilation were less marked, indicating that ventilation with CO is a more effective method with which to study inhibtion of oxidative metabolism. The lung exhibits a Pasteur effectbintain ATP content or its supply for synthetic activity.