IN-VITRO EFFECTS OF BICARBONATE-BUFFERED VERSUS LACTATE-BUFFERED CONTINUOUS AMBULATORY PERITONEAL-DIALYSIS FLUIDS ON PERITONEAL MACROPHAGE FUNCTION

At present, lactate is the most commonly used buffer in peritoneal dia lysis fluids (PDFs), The high lactate concentration in combination wit h low original pH was demonstrated to suppress phagocytic function, We evaluated the in vitro effects of a newly formulated bicarbonate;buff ered PDF containing glycylglycine (BiGG15 and BiGG40; Pierre Fabre Med icament, Castres, France) on peritoneal macrophage (PM0) function, and compared them with those of equiosmolar lactate-buffered PDF (1.5% an d 4.25% glucose; pH 5.4 and pH 7.4) and control buffer, Peritoneal mac rophages were isolated from the effluents of 10 continuous ambulatory peritoneal dialysis patients and tested for luminol- and lucigenin-enh anced chemiluminescence, superoxide (O-2(-)) generation measured by cy tochrome c reduction, killing capacity, and phagocytosis after incubat ion in the PDF used, Exposure of PM0 to lactate-buffered PDF with an o riginal pH of 5.4 resulted in a significant suppression of all PM0 fun ctions measured, compared with bicarbonate- and lactate-buffered PDFs with a pH of 7.4, At physiological pH (7.4), chemiluminescence generat ion of PM0 exposed to BiGG15/40 was significantly higher compared with the corresponding equiosmolar lactate-buffered PDF (1,992 +/- 858 x 1 0(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 signi ficantly different after PM0 exposure to bicarbonate compared with exp osure to lactate-buffered PDF with a neutral pH, Irrespective of the b uffer 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; th ese preliminary in vitro results need to be confirmed in vivo. (C) 199 5 by the National Kidney Foundation, Inc.