Background/Aims: Continuous exposure of the peritoneal membrane to high-glucose (HG) peritoneal dialysis fluids (PDFs) can produce peritoneal mesothelial cells (PMCs) injury. It has been demonstrated that hydrogen sulfide (H2S), the third endogenous gaseous mediator identified after nitric oxide and carbon monoxide, exhibits a potent protective effect on cell activity. We studied the toxic effects of HG PDFs and their reversal by H2S on cultures of rat PMCs. Methods: Synchronized confluent rat PMCs were incubated with 2.5% glucose PDFs with or without NaHS, an H2S donor. Cell viability was assessed by methyl thiazolyl tetrazolium assay and flow cytometry. The level of phospho-p38 mitogen-activated protein kinase (MAPK) was analyzed by immunoblotting. p53, Bax and Bcl-2 mRNA expressions by rat PMCs were detected by real-time PCR. The levels of reactive oxygen species (ROS), superoxide dismutase (SOD) activity and caspase-3 activity were measured. Results: Exposure of rat PMCs to 2.5% glucose PDFs for 24 h resulted in a significant induction of apoptosis, which was attenuated by NaHS. NaHS also restored the 2.5% glucose PDF-induced increase in phospho-p38 MAPK (indices of cellular toxicity). Further investigation of the apoptotic mechanisms in rat PMCs demonstrated that HG activated caspase-3 and upregulated Bax, while it downregulated Bcl-2. All the above responses were prevented by pretreatment with NaHS. Moreover, NaHS reversed the 2.5% glucose PDF-induced increase in ROS generation and decrease in SOD activity. Conclusions: These findings suggest that HG PDFs significantly inhibit rat PMC viability, leading to peritoneal injury. H2S exhibits a potent anti-apoptotic ability by attenuating oxidative stress and inhibiting caspase-3 activation, which in turn restores peritoneal injury. (C) 2014 S. Karger AG, Basel