Inhibition of growth and decreased survival of B104 rat neuroblastoma cells after exposure to hyperbaric oxygen.

The toxic effects of hyperbaric oxygen (HBO) on growth and survival of B104 rat neuroblastoma cells were investigated. Cells in log phase growth were incubated at 37 degrees C with 10 atm O2 for 1 to 4 h. After exposure to HBO, cells were monitored for their subsequent growth and survival. Two hours of exposure caused a slowing of growth, which returned to normal by the end of the 7th d of the postexposure period. Exposures to O2 of 3 h or longer caused a complete cessation of growth for 4 d after the exposure and very little or no recovery after this period. Increased hydrostatic pressure for 6 h using helium as the inert gas had no effect on growth. A colony formation assay was used to quantitate the degree of cell death induced by HBO. The resulting survival curve was of the exponential type with a broad shoulder between 0 to 2.5 h of exposure to 10 atm O2. The curve fell off sharply at 2.5 h with an exponential decrease in survival when the exposure to HBO was extended to 4 h. At 2 h about 50% of cells were killed, but at 4 h only 2% survived the treatment. These results show that the depression of the growth rate by HBO is related to the number of cells that are killed by the exposure. This system provides a model in which the molecular and cellular effects of HBO can be investigated.