Rohn T T, Hinds T R, Vincenzi F F
Department of Pharmacology, School of Medicine, University of Washington, Seattle 98195.
Biochem Pharmacol. 1993 Aug 3;46(3):525-34. doi: 10.1016/0006-2952(93)90530-a.
Preincubation of red blood cell membranes in the presence of ferrous sulfate and EDTA resulted in both a concentration- and time-dependent inhibition of the Na+/K+ pump ATPase, basal Ca2+ pump ATPase, and the calmodulin- (CaM) activated Ca2+ pump ATPase. The IC50 for all three ATPases was approximately 2.5 x 10(-5) M iron. The addition to membranes of ferrous iron and EDTA in an approximately 1:1 ratio resulted in conversion to the ferric iron form in several minutes. However, inhibition of the ion pump ATPases and cross-linking of membrane proteins occurred over the course of several hours. The time course of formation of thiobarbituric acid-reactive substances (TBARS) closely paralleled inhibition of the ion pump ATPases. Inhibition of the ion pump ATPases was prevented by the addition of deferoxamine or superoxide dismutase but not by mannitol, or catalase. Both butylated hydroxytoluene and tirilazad mesylate (U74006F) prevented the formation of TBARS, limited the inhibition of the ion pump ATPases, and reduced cross-linking of membrane proteins. These data may be interpreted to suggest that inhibition of ion pump ATPases in plasma membranes may occur as a result of iron-promoted formation of superoxide and subsequent lipid peroxidation, which can be prevented by free-radical scavengers including butylated hydroxytoluene and U74006F.
在硫酸亚铁和乙二胺四乙酸（EDTA）存在的情况下对红细胞膜进行预孵育，导致钠钾泵ATP酶、基础钙泵ATP酶以及钙调蛋白（CaM）激活的钙泵ATP酶受到浓度和时间依赖性抑制。这三种ATP酶的半数抑制浓度（IC50）约为2.5×10⁻⁵ M铁。以大约1:1的比例向膜中添加亚铁离子和EDTA，几分钟内就会转化为三价铁形式。然而，离子泵ATP酶的抑制和膜蛋白的交联在数小时内发生。硫代巴比妥酸反应性物质（TBARS）的形成时间进程与离子泵ATP酶的抑制密切平行。添加去铁胺或超氧化物歧化酶可防止离子泵ATP酶的抑制，但甘露醇或过氧化氢酶则不能。丁基羟基甲苯和甲磺酰替拉扎特（U74006F）都能防止TBARS的形成，限制离子泵ATP酶的抑制，并减少膜蛋白的交联。这些数据可以解释为表明质膜中离子泵ATP酶的抑制可能是由于铁促进超氧化物的形成以及随后的脂质过氧化所致，而包括丁基羟基甲苯和U74006F在内的自由基清除剂可以防止这种情况。
