pyrophosphate and Hemolysis

Anemia in renal insufficiency results in part from impaired erythrocyte formation due to erythropoietin and iron deficiency. Beyond that, renal insufficiency enhances eryptosis, the suicidal erythrocyte death characterized by phosphatidylserine-exposure at the erythrocyte surface. Eryptosis may be stimulated by increase of cytosolic Ca(2+)-activity ([Ca(2+)]i). Several uremic toxins have previously been shown to stimulate eryptosis. Renal insufficiency is further paralleled by increase of plasma phosphate concentration. The present study thus explored the effect of phosphate on erythrocyte death.. Cell volume was estimated from forward scatter, phosphatidylserine-exposure from annexin V binding, and [Ca(2+)]i from Fluo3-fluorescence.. Following a 48 hours incubation, the percentage of phosphatidylserine exposing erythrocytes markedly increased as a function of extracellular phosphate concentration (from 0-5 mM). The exposure to 2 mM or 5 mM phosphate was followed by slight but significant hemolysis. [Ca(2+)]i did not change significantly up to 2 mM phosphate but significantly decreased at 5 mM phosphate. The effect of 2 mM phosphate on phosphatidylserine exposure was significantly augmented by increase of extracellular Ca(2+) to 1.7 mM, and significantly blunted by nominal absence of extracellular Ca(2+), by additional presence of pyrophosphate as well as by presence of p38 inhibitor SB203580.. Increasing phosphate concentration stimulates erythrocyte membrane scrambling, an effect depending on extracellular but not intracellular Ca(2+) concentration. It is hypothesized that suicidal erythrocyte death is triggered by complexed CaHPO4.

Topics: Calcium; Cell Death; Cell Size; Diphosphates; Erythrocytes; Extracellular Fluid; Hemolysis; Humans; In Vitro Techniques; Phosphates; Phosphatidylserines; Stimulation, Chemical

The effect of stone growth inhibitors (citrate, pyrophosphate, ethane diphosphonate, methane diphosphonate, chondroitin sulfate A, chondroitin sulfate C, heparin and ribonucleic acid) on crystal-membrane interactions of whewellite, weddellite, apatite, brushite, struvite, uric acid, monosodium urate and quartz (control) stones was quantitated. As a model for the initial retention of microcrystals by kidney epithelial membranes, crystal-induced membranolysis of red blood cells served as a measure of crystal-membrane interactions. The inhibitors induced changes in hemolytic potential from approximately 320 per cent enhancement to 80 per cent inhibition. No inhibitor behaved the same way for all crystals studied. However, some crystals showed consistent trends in altered hemolytic potential in the presence of inhibitors. These crystals included weddellite and sodium urate, which were inhibited consistently, and apatite and quartz, which were enhanced consistently. Whewellite, uric acid, brushite and struvite exhibited mixed patterns in the altered hemolytic potentials owing to the inhibitors.

Topics: Calcium Oxalate; Chondroitin Sulfates; Citrates; Citric Acid; Crystallization; Diphosphates; Diphosphonates; Erythrocyte Membrane; Etidronic Acid; Hemolysis; Heparin; Humans; RNA; Urinary Calculi

The effects of incubation time and buffers of differing phosphate concentration on the ability of well characterized, synthetic triclinic calcium pyrophosphate dihydrate (CPPD) crystals to cause hemolysis of erythrocytes were determined. Maximum hemolysis was attained between 8-11 h; the percent hemolysis was 79% at a high crystal concentration of 50 mg/ml. The percent hemolysis values decreased with increasing phosphate concentration, which may have been due to adsorbed phosphate ions partially masking or protecting the erythrocyte membrane from a binding interaction with CPPD crystals. CPPD crystals possessed a significant negative surface potential, and we postulate that the CPPD crystal-membrane interaction may be mediated via an electrostatic mechanism.

Topics: Calcium Pyrophosphate; Cell Membrane; Crystallization; Diphosphates; Erythrocyte Membrane; Hemolysis; Humans; Membrane Potentials

Topics: Animals; Calcium; Complement System Proteins; Diphosphates; Erythrocytes; Factor XII; Gout; Hemolysis; Hot Temperature; Humans; Hydrogen-Ion Concentration; Hypoxanthines; Immune Adherence Reaction; Immunoglobulins; Magnesium; Orotic Acid; Properdin; Sheep; Time Factors; Uric Acid

Topics: Acid Phosphatase; Chondrocalcinosis; Diphosphates; Female; Gout; Hemolysis; Humans; Inflammation; Leukocytes; Lysosomes; Male; Membranes; Phagocytosis; Sex Factors; Silicon Dioxide; Uric Acid

Topics: Adenine; Adult; Allopurinol; Animals; Blood Glucose; Carbon Radioisotopes; Diphosphates; Erythrocytes; Guanine; Hemolysis; Humans; Hypoxanthines; Inosine; Purines; Ribose; Species Specificity; Swine; Time Factors

Microcrystals of sodium urate produced direct lysis of erythrocyte membranes, as had been described previously for silica. Calcium pyrophosphate crystals induced modest erythrocyte hemolysis, also, and time-course experiments showed a markedly different reaction curve from those produced by silica and urate. Polyvinylpyridine-N-oxide, a strong hydrogen acceptor, was bound from solution to urate and silica, but not to calcium pyrophosphate crystals; this compound effectively blocked urate and silica, but not calcium pyrophosphate or control hemolysis. Dextran and heparin inhibited urate-but not silica-induced hemolysis. If erythrocyte and lysosome membranes react similarly to these particles, then the absence of phagosomes in gouty synovial fluid leukocytes, and the presence of these structures in pseudogout, may be explained.

Topics: Cell Membrane; Crystallization; Diphosphates; Erythrocytes; Gout; Hemolysis; Humans; Surface Properties; Uric Acid

Topics: Administration, Oral; Adult; Allopurinol; Diphosphates; Erythrocytes; Female; Gout; Hemolysis; Humans; In Vitro Techniques; Male; Middle Aged; Nucleotides; Purines; Pyrazoles; Pyrimidines; Ribose; Uric Acid; Xanthine Oxidase

Topics: Adenosine Triphosphate; Alcohols; Animals; Chromatography, DEAE-Cellulose; Chromatography, Gel; Dialysis; Diphosphates; Erythrocytes; Guanine Nucleotides; Hemolysis; Humans; Hydrogen-Ion Concentration; Kinetics; Male; Metals; Methods; Nucleotides; Phosphoric Monoester Hydrolases; Quaternary Ammonium Compounds; Rabbits; Reticulocytes; Sulfhydryl Compounds; Sulfur; Uracil Nucleotides