Dise C A, Goodman D B
J Biol Chem. 1985 Mar 10;260(5):2869-74.
The relationship between alterations in transmembrane potential, cell volume, and phospholipid fatty acid turnover has been examined in human erythrocytes by treating the cells with the monovalent cation ionophore valinomycin. Valinomycin increases the cellular uptake of tetra[3H]phenylphosphonium ion by erythrocytes, indicating membrane hyperpolarization, and causes net loss of potassium chloride and water from the cells leading to a decrease in cell volume. Treatment of erythrocytes with valinomycin also enhances incorporation of [9, 10-(3)H]oleic acid into phospholipids, primarily diacylphosphatidylethanolamine. After replacing intracellular chloride with sulfate and treating cells with the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonate, exposure to valinomycin results in uptake of tetra[3H]phenylphosphonium ion and stimulation of [9, 10-(3)H]oleic acid incorporation, but, because anion efflux is prevented, no decrease in cell volume occurs. When tetra[3H]phenylphosphonium ion uptake is also prevented by suspending these cells in 125 mM KCl to dissipate the transmembrane potassium gradient, valinomycin still enhances [9, 10-(3)H] oleic acid incorporation into phospholipid. These results suggest that the presence of valinomycin in the membrane directly alters phospholipid fatty acid turnover and that some of the effects of this ionophore on cellular function previously attributed to alterations in transmembrane potential or cellular potassium content may instead be due to altered phospholipid turnover. Since it is possible that valinomycin may directly perturb phospholipid fatty acid turnover in other cells, the possibility that valinomycin-induced alterations in cellular function are due to altered phospholipid turnover rather than membrane hyperpolarization or altered potassium content should be considered in the interpretation of studies employing this ionophore.
通过用单价阳离子离子载体缬氨霉素处理人红细胞，研究了跨膜电位变化、细胞体积和磷脂脂肪酸周转之间的关系。缬氨霉素增加了红细胞对四[³H]苯基鏻离子的细胞摄取，表明膜超极化，并导致细胞中氯化钾和水的净损失，从而导致细胞体积减小。用缬氨霉素处理红细胞还能增强[9,10-(³H)]油酸掺入磷脂，主要是二酰基磷脂酰乙醇胺。在用硫酸盐替代细胞内氯化物并用阴离子转运抑制剂4,4'-二异硫氰基芪-2,2'-二磺酸盐处理细胞后，暴露于缬氨霉素会导致四[³H]苯基鏻离子的摄取和[9,10-(³H)]油酸掺入的刺激，但由于阴离子外流被阻止，细胞体积没有减小。当将这些细胞悬浮在125 mM KCl中以消除跨膜钾梯度从而也阻止四[³H]苯基鏻离子摄取时，缬氨霉素仍然会增强[9,10-(³H)]油酸掺入磷脂。这些结果表明，膜中缬氨霉素的存在直接改变了磷脂脂肪酸周转，并且这种离子载体对细胞功能的一些先前归因于跨膜电位或细胞钾含量变化的影响可能反而归因于磷脂周转的改变。由于缬氨霉素可能直接扰乱其他细胞中的磷脂脂肪酸周转，因此在解释使用这种离子载体的研究时，应考虑缬氨霉素诱导的细胞功能变化是由于磷脂周转改变而非膜超极化或钾含量改变的可能性。
