Abstract: Objective To investigate the mechanism by which hydrogen sulfide (H2S) delays the aging of rat aortic endothelial cells (RAECs). MethodsCells were divided into six groups according to their corresponding treatment: a young group, an old group, a DMSO group, a NaHS group, an ATRA group, and a NaHS+ATRA group. The aging of the cells was detected by β-galactosidase (β-gal) staining. The level of thiolated Keap1 was determined by a modified biotin method. The amounts of nuclear transcription factor Nrf2 and superoxide dismutase 2 (SOD2) were detected by Western blotting. ResultsCompared with the young group, the positive rate of β-gal staining was remarkably increased in the old group (P<0.01), which was then reduced after treatment with exogenous H2S (NaHS) (P<0.01). Pre-treatment with Nrf2 blocker all trans retinoic acid (ATRA) could result in decreases in the positive rate of β-gal staining in old group (P<0.01). Compared with the old group, the levels of sulfur thiolated Keap1, Nrf2, SOD2 were increased in NaHS-treated endothelial cells (P<0.01). Pre-treatment with ATRA could result in remarkable decreases in the amounts of Nrf2 and SOD2 in endothelial cells (P<0.01). ConclusionsExogenous H2S increases the levels of sulfur thiolated Keap1 in endothelial cell, weakens the inhibitory effect of Keap1 on Nrf2, stimulate the entry of Nrf2 into the nucleus, so as to increase the expression of downstream SOD2 protein, enhance the antioxidative stress in endothelial cell, and delay the aging process of the cells .