Balke N E, Hodges T K
Department of Botany and Plant Pathology, Purdue University, West Lafayette, Indiana 47907.
Plant Physiol. 1979 Jan;63(1):42-7. doi: 10.1104/pp.63.1.42.
Effects of diethylstilbestrol (DES) on ion fluxes in oat roots (Avena sativa L.) were investigated by measuring K(+) and Cl(-) absorption and K(+) efflux. DES rapidly decreased the absorption of K(+) ((86)Rb) and (36)Cl(-) by excised roots; 10(-4) molar DES inhibited Cl(-) absorption in 1 minute and K(+) absorption in 1 to 2 minutes. With a 10-minute incubation period, K(+) and Cl(-) absorption were inhibited 50% by 1.1x10(-5) molar and 8.4x10(-6) molar DES, respectively. Treatment for 3 minutes with 10(-4) molar DES caused irreversible inhibition of K(+) absorption. Increasing concentrations of KCl in the absorption media decreased the DES inhibition. Experiments with the DES analogs, DES dipropionate, dienestrol and hexestrol, showed that the steric configuration and the hydroxyl group of the DES molecule are important in determining the inhibitory capacity of the compound.DES increased the efflux of (86)Rb from excised roots only after a 10-minute lag period. In 10(-4) molar DES, roots lost 82% of their radionuclide content in 1 hour. Comparison of efflux curves for roots loaded for 20 hours and those loaded for 15 minutes suggested that DES increased the permeability of the plasma membrane after about 10 minutes and the permeability of the tonoplast after 10 to 20 minutes. Oligomycin and dinitrophenol also increased the loss of (86)Rb, but the lag period was about 4 hours.The rapid effect of DES on ion absorption and the slower effect on ion efflux suggest that DES initially inhibits ion uptake by affecting the transport mechanism at the plasma membrane in some manner other than alteration of membrane permeability.
通过测量钾离子（K⁺）和氯离子（Cl⁻）的吸收以及钾离子外流，研究了己烯雌酚（DES）对燕麦根（燕麦）离子通量的影响。DES迅速降低了离体根对K⁺（⁸⁶Rb）和³⁶Cl⁻的吸收；10⁻⁴摩尔的DES在1分钟内抑制Cl⁻吸收，在1至2分钟内抑制K⁺吸收。在10分钟的孵育期内，1.1×10⁻⁵摩尔和8.4×10⁻⁶摩尔的DES分别抑制了50%的K⁺和Cl⁻吸收。用10⁻⁴摩尔的DES处理3分钟导致K⁺吸收的不可逆抑制。吸收介质中KCl浓度的增加降低了DES的抑制作用。用DES类似物己烯雌酚二丙酸酯、dienestrol和己烷雌酚进行的实验表明，DES分子的空间构型和羟基在决定该化合物的抑制能力方面很重要。DES仅在10分钟的延迟期后增加了离体根中⁸⁶Rb的外流。在10⁻⁴摩尔的DES中，根在1小时内损失了82%的放射性核素含量。对加载20小时的根和加载15分钟的根的外流曲线进行比较表明，DES在大约10分钟后增加了质膜的通透性，在10至20分钟后增加了液泡膜的通透性。寡霉素和二硝基苯酚也增加了⁸⁶Rb的损失，但延迟期约为4小时。DES对离子吸收的快速作用和对离子外流的较慢作用表明，DES最初通过以某种不同于改变膜通透性的方式影响质膜上的转运机制来抑制离子摄取。
