Shortening of the in vitro lifespan of human diploid fibroblasts exposed to hyperbaric oxygen.

Serially cultivated WI-38 cells were exposed to 50 atm of oxygen for one hour at each passage after they reached 31 population doublings (PDs). They phased out at 51 PDs while the untreated and nitrogen-exposed cells at 56 PDs. The early-passage cells were found to be resistant to 50 atm of oxygen. The in vitro lifespan of WI-38 cells remained unchanged on less than eight exposures given before 46 PDs, and shortened in proportion to the number of extra exposures given after 46 PDs in addition to the seven exposures. For TIG-1 cells treated doubly with oxygen at late passages, modal cell volume began to increase at 54 PDs, and for the nitrogen-treated cells at 59 PDs. The in vitro aging of late-passage human cells exposed to hyperbaric oxygen seems to be accelerated.