Animal study was performed to determine the changes in rat lung permeability in hyperoxic condition. 3 groups of rats (n=8 each) were exposed to 100% oxygen for 24 hr(group 2), 48 hr(group 3) and 72 hr(group 4), respectively, and compared with
control
(group 1 at room air, n=). The time course of development of solute flux was evaluated by (the clearance of 99m Tc-labeled dietylenetriamine pentaacetate (99mTc-DTPA) from the lung. Afterwards, bronchoalveolar lavage (BAL) was performed to
measure
the
concentration of albumin and determine the evidence of cell injury and inflammation in lung. BAL fluids were analyzed to determine several markers of cell injury and inflammation including total and differential cell counts, lactate dehydrogenase
(LD),
alkaline phosphatase (ALP), extracellular potassium (k+) and globulin (total protein minus albumin).
99mTc-DTPA clearance was significantly increased by exposure for 48 hours of hyperoxia. Albumin concentration ratio (BAL albumin concentration divided by serum albumin concentration) was increased sharply after 48 hr. Significant changes in WBC
counts
and differential counts were not found until 48 hr of hyperoxia. Elevated LD concentration was bserved at 48 hr and thereafter, and ALP, K+, and globulin concentration ratio (BAL globulin / serum globulin) was significantly high only in group 4.
Mortality was not observed until 72 of 8 rats were dead.
It is concluded that significant 99mTc-DTPA clearance, and cellular and biochemical findings of BAL could not be observed until 48 hr in rats exposed to 100% oxygen.
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