Improved cytosolic free calcium mobilization and superoxide production in bicarbonate-based peritoneal dialysis solution

Background. Intraperitoneal phagocytes play animportant role in local host defence to prevent CAPD peritonitis. Theintracellular calcium [Ca²⁺]i is thought to beinvolved in the regulation of various cell functions. This study thereforeinvestigates the effect of lactate-based dialysis solution (LBDS) andbicarbonate-based dialysis solution (BBDS) on cytosolic free calciummobilization and superoxide production (SP) as important steps in signaltransduction and bacterial killing. Methods. Westudied changes in [Ca²⁺]i and SP followingstimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP) inpolymorphonuclear neutrophils (PMNs) incubated in either LBDS-pH 5.2, LBDSadjusted to pH 7.4, 1:10 diluted spent and fresh LBDS or BBDS-pH 7.4 withdifferent glucose concentrations, comparing the data with cells treatedwith Hanks buffer (HBSS) pH 7.4 as control. To elucidate the effect ofglucose and lactate PMNs were additionally incubated in HBSS-pH 7.4,containing glucose (HBSS-Glu-pH 7.4) or lactate (HBSS-Lact-pH 7.4) in thesame concentrations as contained in CAPD solutions and tested as above.PMNs were isolated from healthy blood donors and incubated with dialysissolution 10 min prior to stimulation with fMLP.Results. [Ca²⁺]i mobilizationand SP were completely inhibited in PMNs incubated in LBDS pH 5.2. pHadjustment of LBDS to 7.4 and 1:10 dilution of spent and fresh LBDScorrected some of the suppression of the calcium influx and superoxideproduction. BBDS pH 7.4, however, preserved physiological cell functionsignificantly better at low (1.5 and 2.3%) glucose concentrations.Conclusion. In comparison to conventionallactate-based dialysis solution, pH adjusted and 1:10 diluted LBDS,bicarbonate-based dialysis solution is more biocompatible since itpreserves significantly better neutrophil cell functions.