Altered DNA repair in fibroblasts from aged rats.

The role of DNA repair in the aging process was studied using fibroblast cultures derived from rats at the beginning (3 weeks) and at the end (2 years) of their potential lifespan. The effect of treatment of the cultures with the DNA-damaging agent, ethylnitrosourea, on the integrity of the pre-existing parental DNA and on de novo DNA synthesis was determined using the alkaline elution method. It was found that drug treatment resulted in lower levels of fragmentation of parental DNA and in decreased fractions of short daughter strands in cells derived from old relative to young animals. These results indicate an alteration of the processing of DNA damage in cells derived from aged rats.