IN-VITRO EFFECTS OF BICARBONATE AND BICARBONATE-LACTATE BUFFERED PERITONEAL-DIALYSIS SOLUTIONS ON MESOTHELIAL AND NEUTROPHIL FUNCTION

The inclusion of bicarbonate in the formulation of peritoneal dialysis solutions may avoid the in vitro impairment of certain cell functions seen with acidic lactate-based fluids. The supranormal physiological levels of HCO3 and P-CO2 inherent in such formulations may, however, n ot be biocompatible. This study compared the in vitro biocompatibility of a pH 5.2 lactate-based formulation with formulations containing ei ther 40 mM lactate at pH 7.4, 38 mM HCO3- at pH 6.8 (P-CO2 at approxim ately 240 mm Hg) or 7.4 (P-CO2 at approximately 60 mm Hg), and 25 mM H CO3 plus 15 mM lactate at pH 6.8 (P-CO2 at approximately 160 mm Hg) or 7.4 (P-CO2 at approximately 40 mm Hg). Significant release of lactate dehydrogenase or decrease in ATP content by human peritoneal mesothel ial cells (HPMC) and human peripheral polymorphonuclear leukocytes (PM N) after a 30-min exposure to each test solution was only seen with th e pH 5.2 lactate-based fluid. The ATP content of HPMC exposed to this fluid returned to control levels after 30 min of recovery in M199 cont rol medium but showed a trend toward decreasing ATP content at 240 min . Similarly, interleukin (IL)-1 beta-induced IL-6 synthesis by HPMC wa s also only significantly reduced by the pH 5.2 lactate solution. PMN chemiluminescence was unaffected by 30-min exposure to all test soluti ons except for the pH 5.2 lactate formulation. Staphylococcus epidermi dis phagocytosis was reduced to between 46 to 57% of control with all test solutions except the pH 5.2 lactate solution, which further suppr essed the chemiluminescence response to 17% of control. These data sug gest that short exposure to supranormal physiological levels of HCO3- and P-CO2 does not impair HPMC or PMN viability and function, Furtherm ore, neutral pH lactate-containing solutions show equivalent biocompat ibility to bicarbonate-based ones.