Kobayashi A, Hayashi H, Watanabe H, Miyata H, Kurata C, Yamazaki N
Third Department of Internal Medicine, Hamamatsu University School of Medicine, Japan.
Bratisl Lek Listy. 1991 Feb;92(2):59-65.
Free radicals can affect lipids of membranes by initiating peroxidation. Since alterations in membrane fluidity can modulate membrane functions including ion permeability, the effects of free radicals on the intracellular Ca2+ level ([Ca2+]i) and membrane fluidity were studied. Human erythrocytes were spin-labeled with 5-DSA and the membrane fluidity was quantified by ESR during application of oxygen-derived free radicals. The morphology was observed by the scanning electron microscopy. The effects of H2O2 on [Ca2+]i were studied using single guinea pig ventricular myocytes and fura-2 AM. Superoxide and H2O2 (10(-3) and 10(-4) M) induced a decrease in membrane fluidity and morphological changes of erythrocytes. [Ca2+]i significantly increased from the control value (53 +/- 4 nmol/litre) to 110 +/- 29 nmol/litre when the cells were shortened, and to 130 +/- 26 nmol/litre before cells became rounded. This study showed that [Ca2+]i was significantly increased by oxygen-derived free radicals, possibly by lipid peroxidation of the cell membrane. During perfusion with H2O2 however, the increase in [Ca2+]i was not pronounced. Therefore, we suspect that the mechanism of cell injury due to free radicals may be a combination of direct cell membrane injury and Ca2+ overload rather than intracellular Ca2+ overload.
自由基可通过引发过氧化反应影响细胞膜脂质。由于膜流动性的改变可调节包括离子通透性在内的膜功能，因此研究了自由基对细胞内钙离子水平（[Ca2+]i）和膜流动性的影响。用人红细胞与5-DSA进行自旋标记，并在施加氧衍生自由基期间通过电子自旋共振（ESR）对膜流动性进行定量分析。通过扫描电子显微镜观察形态。使用单个豚鼠心室肌细胞和fura-2 AM研究了H2O2对[Ca2+]i的影响。超氧化物和H2O2（10^(-3)和10^(-4) M）可导致红细胞膜流动性降低和形态改变。当细胞缩短时，[Ca2+]i从对照值（53±4 nmol/升）显著增加至110±29 nmol/升，在细胞变圆之前增加至130±26 nmol/升。本研究表明，氧衍生自由基可显著增加[Ca2+]i，可能是通过细胞膜的脂质过氧化反应。然而，在用H2O2灌注期间，[Ca2+]i的增加并不明显。因此，我们怀疑自由基导致细胞损伤的机制可能是直接细胞膜损伤和Ca2+过载的组合，而非细胞内Ca2+过载。
