de Peyster A, Hyslop P A, Kuhn C E, Sauerheber R D
Biochem Pharmacol. 1986 Oct 1;35(19):3293-300. doi: 10.1016/0006-2952(86)90426-0.
The effects of gossypol on membrane structure and membrane-associated functions were studied to explore possible reasons for the ability of gossypol to disrupt cellular processes, many of which involve intracellular and plasma membranes. The experiments reported here measured the effects of gossypol on membrane order, permeability, and hexose transport. Electron spin resonance (ESR) studies of I(12,3) nitroxide fatty acid spin-labeled unilamellar liposomes showed that exposure to 0.05 to 4 mM gossypol caused a dose-dependent increase in the polarity-corrected order parameter (S), indicating reduced motional freedom of the spin probe after exposure to gossypol. This observation is consistent with the idea that gossypol causes an ordering or "condensing" of the membrane lipid matrix. Gossypol-induced changes in order parameter in phosphatidylcholine:cholesterol liposomes varied depending on the liposome composition. Liposomes exposed to gossypol also showed increasing permeability to glycerol as the gossypol:phospholipid ratio increased up to 10 mole %. Higher concentrations of gossypol were less effective at enhancing permeability. In addition, basal and insulin-stimulated 2-deoxy-D-[3H]glucose transport were inhibited in freshly isolated rat adipocytes incubated with gossypol at 37 degrees. Half-maximal inhibition occurred at approximately 0.2 mM for uptake in both the presence and absence of 40 ng/ml insulin. Microscopic observation of the cells under low power (40 X) confirmed that diminished hexose transport was not simply due to breakage of the adipocyte plasma membrane, resulting in a decrease in intact cell population and decreased accumulation of label in the gossypol-treated cells. Gossypol produced no significant changes in numbers of intact cells or gross morphology at the concentrations tested. We suggest that ordering and increased permeability of the lipid regions of plasma and subcellular membranes may contribute to some of the toxic and pharmacologic properties of gossypol. Our results also support the idea that gossypol may exert more pronounced effects in cells that are most sensitive to variations in availability of glucose substrates for energy metabolism.
研究了棉酚对膜结构和膜相关功能的影响，以探究棉酚破坏细胞过程能力的可能原因，其中许多细胞过程涉及细胞内和质膜。本文报道的实验测量了棉酚对膜有序性、通透性和己糖转运的影响。对I(12,3)氮氧化物脂肪酸自旋标记的单层脂质体进行电子自旋共振（ESR）研究表明，暴露于0.05至4 mM棉酚会导致极性校正有序参数（S）呈剂量依赖性增加，这表明暴露于棉酚后自旋探针的运动自由度降低。这一观察结果与棉酚导致膜脂质基质有序化或“凝聚”的观点一致。棉酚诱导的磷脂酰胆碱：胆固醇脂质体有序参数的变化取决于脂质体组成。暴露于棉酚的脂质体对甘油的通透性也随着棉酚：磷脂比例增加至10摩尔%而增加。更高浓度的棉酚在增强通透性方面效果较差。此外，在37℃下用棉酚孵育的新鲜分离的大鼠脂肪细胞中，基础和胰岛素刺激的2-脱氧-D-[3H]葡萄糖转运受到抑制。在有和没有40 ng/ml胰岛素的情况下，摄取的半数最大抑制浓度约为0.2 mM。低倍（40倍）显微镜观察细胞证实，己糖转运减少并非仅仅是由于脂肪细胞质膜破裂，导致完整细胞数量减少以及棉酚处理细胞中标记物积累减少。在所测试的浓度下，棉酚对完整细胞数量或总体形态没有显著影响。我们认为，质膜和亚细胞膜脂质区域的有序化和通透性增加可能是棉酚某些毒性和药理特性的原因。我们的结果还支持这样一种观点，即棉酚可能在对能量代谢中葡萄糖底物可用性变化最敏感的细胞中发挥更显著的作用。
