Serum fibronectin is elevated during normobaric and hyperbaric oxygen exposure in rats.

Serum fibronectin concentration was measured by immunoelectrophoresis in rats exposed to 1 atmosphere absolute (ata) of oxygen for 24 to 72 h and at 30-min intervals during 1 to 5 h of exposure to 4 ata O2. At 1 ata O2, there was a progressive increase in serum fibronectin, which became significant at 48 h and was 2.5 times the control value by 72 h (p less than 0.01). At 4 ata O2, the rise in serum fibronectin was significant at 2 h, and was followed by an accelerated rate of increase to 5 h, at which time serum fibronectin concentration was 1.75 times the control value (p less than 0.05). By SDS-polyacrylamide gel electrophoresis and crossed immunoelectrophoresis, there was no evidence of fragmentation of fibronectin. This study demonstrated a progressive increase in serum fibronectin in the oxygen-exposed rat. The magnitude and course of the increase suggest increased synthesis and secretion of intact fibronectin molecules.