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Effects of bicarbonate buffered dialysate on human peritoneal mesothelial cell intracellular calcium homeostasis
Author(s) -
BIRD STEPHEN D,
WALKER ROBERT J
Publication year - 2003
Publication title -
nephrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 61
eISSN - 1440-1797
pISSN - 1320-5358
DOI - 10.1046/j.1440-1797.2003.00150.x
Subject(s) - bicarbonate , homeostasis , calcium , citric acid , intracellular ph , intracellular , ionophore , hepes , calcium metabolism , biochemistry , chemistry , biophysics , endocrinology , medicine , biology
SUMMARY: 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 µmol/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.