Swick A G, Swick R W
Am J Physiol. 1986 Aug;251(2 Pt 1):E192-5. doi: 10.1152/ajpendo.1986.251.2.E192.
GDP binding to brown adipose tissue (BAT) mitochondria increased more than twofold in 20 min when rats were moved from 27 to 4 degrees C. When animals housed at 4 degrees C for 2 h were returned to 27 degrees C, GDP binding decreased sharply in 20 min and returned to control levels in 2 h. These results are consistent with a rapid unmasking and remasking of GDP binding sites. GDP binding to mitochondria from warm and acutely cold treated rats was not modified by prior swelling, by freeze-thawing, nor by sonication of the mitochondria before assay. GDP-inhibitable proton conductance, as measured by passive swelling, was unaffected by this brief exposure to cold but more than doubled in rats kept at 4 degrees C for 10 days. We hypothesize that the rate of GDP-inhibitable swelling may be a reflection of uncoupling protein concentration in the BAT mitochondria, whereas physiological thermogenic activity is more appropriately indicated by GDP binding. The alterations in binding activity appear not to be due to changes in the mitochondrial membrane integrity.
当大鼠从27摄氏度转移至4摄氏度时，GDP与棕色脂肪组织（BAT）线粒体的结合在20分钟内增加了两倍多。当在4摄氏度饲养2小时的动物回到27摄氏度时，GDP结合在20分钟内急剧下降，并在2小时内恢复到对照水平。这些结果与GDP结合位点的快速暴露和重新掩盖一致。在测定前，用预先膨胀、冻融或线粒体超声处理均未改变来自温暖和急性冷处理大鼠的线粒体与GDP的结合。通过被动膨胀测量的GDP抑制性质子传导不受这种短暂冷暴露的影响，但在4摄氏度饲养10天的大鼠中增加了一倍多。我们推测，GDP抑制性膨胀速率可能反映了BAT线粒体中解偶联蛋白的浓度，而生理产热活性更恰当地由GDP结合来表示。结合活性的改变似乎不是由于线粒体膜完整性的变化。
