Monocarboxylate Transporter-1 Mediates the Protective Effects of Neutral-pH Bicarbonate/Lactate-Buffered Peritoneal Dialysis Fluid on Cell Viability and Apoptosis

We investigated the effects of bicarbonate/lactate-buffered peritoneal dialysis fluid (B/L-PDF) and lactate-buffered PDF (L-PDF) on cell viability and apoptosis, focusing on monocarboxylate transporters (MCTs). MCT-1 transports lactate into cells. Cell viability and apoptosis of human peritoneal mesothelial cells (HPMCs) were examined by water-soluble tetrazolium salt-1 and TUNEL assays, respectively. The relative number of viable HPMCs was significantly decreased by L-PDF at 48 h (8.8 ± 0.4%) compared with cells cultured in M199, but not by B/L-PDF (66.7 ± 1.1%). Apoptosis was markedly induced by L-PDF at 48 h (69.3 ± 16.2%), but not by B/L-PDF (2.6 ± 0.3%). Knockdown of MCT-1 by small interfering RNA (siRNA) attenuated the L-PDF-induced reduction of viable cells and increased apoptosis compared with control siRNA, but MCT-4 knockdown had no effect. B/L-PDF had lesser effects on cell viability and apoptosis of HPMCs compared with L-PDF. These results suggest that B/L-PDF biocompatibility occurs by avoiding the induction of apoptosis in HPMCs.