In vitro effects of bicarbonate- versus lactate-buffered continuous ambulatory peritoneal dialysis fluids on peritoneal macrophage function

At present, lactate is the most commonly used buffer in peritoneal dialysis fluids (PDFs), The high lactate concentration in combination with low original pH was demonstrated to suppress phagocytic function, We evaluated the in vitro effects of a newly formulated bicarbonate;buffered PDF containing glycylglycine (BiGG15 and BiGG40; Pierre Fabre Medicament, Castres, France) on peritoneal macrophage (PM0) function, and compared them with those of equiosmolar lactate-buffered PDF (1.5% and 4.25% glucose; pH 5.4 and pH 7.4) and control buffer, Peritoneal macrophages were isolated from the effluents of 10 continuous ambulatory peritoneal dialysis patients and tested for luminol- and lucigenin-enhanced chemiluminescence, superoxide (O-2(-)) generation measured by cytochrome c reduction, killing capacity, and phagocytosis after incubation in the PDF used, Exposure of PM0 to lactate-buffered PDF with an original pH of 5.4 resulted in a significant suppression of all PM0 functions measured, compared with bicarbonate- and lactate-buffered PDFs with a pH of 7.4, At physiological pH (7.4), chemiluminescence generation of PM0 exposed to BiGG15/40 was significantly higher compared with the corresponding equiosmolar lactate-buffered PDF (1,992 +/- 858 x 10(3) cpm/10(4) cells v 856 +/- 398 x 10(3) cpm/10(4) cells; P < 0.004), O-2(-) generation, killing capacity, and phagocytosis were not significantly different after PM0 exposure to bicarbonate compared with exposure to lactate-buffered PDF with a neutral pH, Irrespective of the buffer used, high-osmolality PDFs suppressed PM0 function significantly more than low-osmolar PDFs, In conclusion, bicarbonate-buffered PDFs are less detrimental to PM0) function than lactate-containing PDFs; these preliminary in vitro results need to be confirmed in vivo. (C) 1995 by the National Kidney Foundation, Inc.