title: Effects of bicarbonate buffered dialysate on human peritoneal mesothelial cell intracellular calcium homeostasis.
abstract: This study compares the biocompatibility of two bicarbonate-based peritoneal dialysis (PD) solutions using the measurement of intracellular free calcium (Ca(i)2+)) as a sensitive parameter of cell function in human peritoneal mesothelial cells (hPMC). Fura-2-loaded hPMC suspensions were exposed to bicarbonate (38 mmol/L) and bicarbonate (25 mmol/L), lactate-buffered PD (15 mmol/L) solutions at pH 7.4 and compared with Krebs-Ringer physiological saline (KRS; pH = 7.4). Resting Ca(i)2+ values and 4br-A23187 (1.0 micro mol/L) induced transients were compared in treatment and control groups. In separate studies, the effect that low saline pH had on Ca(i)(2+) homeostasis was examined. Suspended cells or cells attached to coverslips were bathed in citric acid-phosphate (McIllvaine's) buffered saline (MBS, pH = 7.4). Cells were acidified (pH = 5.3) with citric acid and then challenged with ionophore. Ionophore challenge produced a significantly reduced Ca(i)2+ transient response in cells exposed to the bicarbonate/lactate fluid compared with bicarbonate or KRS. Acidified cell suspensions produced a small monophasic Ca(i)2+ transient rise that was short lived. Gradual recovery of MBS to pH 7.4 produced no changes to Ca(i)2+ homeostasis of cell monolayers. Ionophore treatment produced a biphasic response identical to cells bathed in KRS. This study has demonstrated that short-term exposure to bicarbonate did not alter Ca(i)2+ homeostasis directly, or subsequent modulation of intracellular pH. The MBS system provided a reliable method of modifying the external pH during continuous Ca(i)2+ measurement.
authors.affiliation: Department of Medical and Surgical Science, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand. sdbird@hotmail.com
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Bird
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Walker
mesh_terms: D001639:Bicarbonates / Q000737:chemistry / Q000494:pharmacology*; D002021:Buffers; D000001:Calcimycin / Q000031:analogs & derivatives / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D002951:Citrates / Q000494:pharmacology; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D015314:Dialysis Solutions / Q000737:chemistry / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006706:Homeostasis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D007552:Isotonic Solutions / Q000737:chemistry / Q000494:pharmacology*; D007773:Lactates / Q000494:pharmacology; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
chemical_list: D001639:Bicarbonates; D002021:Buffers; D002951:Citrates; D015314:Dialysis Solutions; D007476:Ionophores; D007552:Isotonic Solutions; C051865:Krebs-Ringer solution; D007773:Lactates; D000001:Calcimycin; C033170:4-bromo-A-23187; D002118:Calcium