AJP - Endocrinology and Metabolism, Vol 250, Issue 2 131-E136, Copyright © 1986 by American Physiological Society
Rat lung metabolism after 3 days of continuous exposure to 0.6 ppm ozone
D. J. Bassett and E. Bowen-Kelly
Continuous exposure of rats to low concentrations of ozone has previously
been associated with enhanced metabolic enzyme activities, when measured in
lung homogenates. In this study, metabolic rates were measured in intact
perfused lungs with altered pathology brought about by 3 days continuous
exposure to 0.6 ppm ozone. Increased metabolism of ozone-exposed lungs was
indicated by a twofold enhancement in glucose utilization, associated with
a 62% increase in lactate formation and a 166% increase in the rate of
14CO2 production from D-[U-14C]glucose from control values of 5.2 +/- 0.5
mumol lactate and 4.4 +/- 0.6 mumol 14CO2/h per lung (+/- SE, n = 4),
respectively. Mitochondrial metabolism was separately assessed by
measurements of 14CO2 production from [U-14C]-pyruvate, which was found not
to be significantly altered by ozone exposure, although homogenate oxygen
uptake in the presence of succinate was significantly enhanced by 57%.
These changes in intermediary metabolism could be correlated with increased
glucose carbon incorporation into lipid and elevated activity of
glucose-6-phosphate dehydrogenase. The observed elevated metabolic rates
were consistent with the energy and synthetic needs of a lung during repair
of ozone-induced damage.
