Transient increased extracellular release of H2O2 during establishment of UVB-induced premature senescence.

In this work, we found that extracellular release of H(2)O(2) is 1.5- to 6-fold higher in skin human diploid fibroblasts exposed to UVB in conditions inducing premature senescence when compared to control cells without exposure to UVB. The apparent decrease in H(2)O(2) production from 0 to 72 h after the last exposure to UVB was not due to increased enzymatic activity of catalase or glutathione peroxidase.