The study of Ca2+ influx in human erythrocytes in isotonic polyethylene (glycol) 1500 (PEG-1500) and sucrose media.
Effects of isotonic solutions of polyethylene (glycol) 1500 (PEG-1500) and sucrose on Ca2+ influx into ATP-depleted red blood cells were studied using the Ca2+ -sensitive fluorescent dye fura-2AM. When incubated in isotonic low ionic strength media (containing 2 mM CaCl2 in addition to sucrose and PEG-1500), the initial rate of Ca2+ influx was higher than that for the cells in physiological (normal ionic strength) medium. After 20 minutes of incubation in the PEG-1500-containing solution, a 10-fold increase of Ca2+ influx was observed, whereas in the sucrose medium the rate of Ca2+ influx decreased compared to that in physiological medium. 1H-NMR data provided no evidence of direct interaction between PEG-1500 and the erythrocyte membrane. Moreover, PEG-1500 did not affect lipid peroxidation (LPO) induction in erythrocyte membranes. We propose that a change in the hydrogen environment of Ca2+ -ATPase of the erythrocytes suspended in the PEG-1500 solution is the primary cause of altered Ca2+ homeostasis in these cells. The activation of the Ca2+ -ATP-ase in sucrose medium may result in an incomplete suppression of the Ca2+-pump activity in ATP-depleted cells, which is accelerated when calmodulin binds with the Ca2+-ATP-ase under the conditions of rapid Ca2+ accumulation.
Kucherenko
Y V
YV
Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, Kharkiv. cryo@online.kharkov.ua
Bernhardt
I
I
D000255:Adenosine Triphosphate / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D007552:Isotonic Solutions; D015227:Lipid Peroxidation / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D011092:Polyethylene Glycols / Q000737:chemistry / Q000494:pharmacology*; D013395:Sucrose / Q000737:chemistry / Q000494:pharmacology*
D003470:Culture Media; D007552:Isotonic Solutions; D011092:Polyethylene Glycols; D013395:Sucrose; D000255:Adenosine Triphosphate; D002118:Calcium