Abstract: Exogenous cholesterol was added in two ways:one was that exogenous cholesterol was absorbed by root system during water culture of rice$ the other was adding it directly to the prepared mitochondria of control rice root apex, and incubating it at 8℃ for 30 minutes. The ATPase activity was then determined. The result indicated that exogenous cholesterol in the given range of concentrations increased the ATPase activity of mitochondria in rice root apex in the either Way. It was also observed that exogenous cholesterol markedly decreased the break point temperatures of ATPase AEa of mitochondria, into which the cholesterol was absorbed by root system, from 27.7℃ and 15.5℃ in the control to 24.5℃ and 12.7℃, respectively; and that of the mitochondria, with which the cholesterol was directly incubated, decreased to 18.8℃ and 9.6℃, respectively. This result indicates that the proper amount of exogenous cholesterol not only has an apparent accelerating effect on the ATPase activity in rice apex mitochondria, but also a regulating effect on the decrease of phase transition temperature of mitochondria membrane.

Key words: Cholesterol, Mitochondria ATPase, Membrane phase transition temperature

摘要： 外源胆固醇无论是通过根系吸收或是直接与离体线粒体一起温育的方式,在试验浓度范围内均能提高水稻根端线粒体ATP酶的活力,同时观察到外源胆固醇能明显降低ATP酶表现活化能(Apparent activation energy,AEa)在Arrhenius图上的折点温度。其中通过根系吸收进入线粒体膜内后,其线粒体ATP酶AEa的两个折点温度由对照的27.7℃和15.5℃分别降低到24.5℃和12.7℃;直接与离体线粒体一起温育的两个折点温度分别降低到18.8℃和9.6℃。试验结果证明,适量的外源胆固醇不仅对水稻根端线粒体ATP酶活力具有明显的促进作用,而且对降低线粒体膜脂的相变温度也有明显的调节作用。

关键词: 胆固醇, 线粒体ATP酶, 膜相变温度