急性冷暴对大鼠肝线粒体H+转运ATP酶及膜流动性的影响

Effects of acute cold exposure on mitochondrial energy transition function in hepatocytes in rats

目的：为进一步探讨急性冷暴过程中肝线粒体功能的变化．方法：观察雄性大鼠在室温（１８℃），冷暴（－１０℃）１５ｍｉｎ，６０ｍｉｎ和６０ｍｉｎ后室温１５ｍｉｎ时肝亚线粒体膜流动性，Ｈ＋转运ＡＴＰ酶活性及其对寡霉素敏感性的变化．结果：大鼠在冷暴１５ｍｉｎ时，膜流动性即开始降低（０．２５０±０．００５对０．２５７±０．００５），Ｈ＋转运ＡＴＰ酶活性及其对寡霉素的敏感性也明显下降［（７．６７±１．００）对（６．５９±１．００）μｍｏｌ／（ｍｉｎ·ｍｇ），（９８．９３±１．４４）对（９６．２３±１．１０）％］，在冷暴６０ｍｉｎ时，三项指标下降更明显，室温恢复１５ｍｉｎ后，三项指标仍保持在较低水平．结论：冷应激可以导致肝线粒体Ｈ＋转运ＡＴＰ酶活性的降低，降低的原因可能是冷应激导致的肝线粒体内膜流动性下降，引起了Ｈ＋转运ＡＴＰ酶结构的变化，进而影响酶的活性．

Objective: To study the changes of mitochondrial function in hepatocytes during acute cold exposure. Methods: Forty male SD rats were randomized into 4 groups. Group 1 served as the control group, and rats of group 2 and 3 were treated in the temperature of -10℃ for 15 and 60 min, respectively. Group 4 was treated in the temperature of -10℃ for 60 min and in the room temperature for 15 min. Immediately after treatment, livers were collected for examination of the fluidity of submitochondrial membrane in hepatocytes, the activity of H + transporting ATPase and its sensitivity to oligomycin. Results: When rats were exposed in cold environment to 15 min, the fluidity of submitochondrial membrane, the activity of H + transporting ATPase and its sensitivity to oligomycin was lower than those of the control [(0.250±0.005) vs (0.257± 0.005 ), (7.67±1.00) vs (6.59±1.00) μmol/(min·mg), (98.83±1.44) vs (96.23±1.10)%]. When rats were exposed in cold environment to 60 min, there were significant reduction in the three indices. When rats recovered in room temperature for 15 min, the three indices still remained lower. Conclusions: The above mentioned findings indicated that acute cold exposure might lead to changes in the activity of H + transporting ATPase in hepatocellular mitochondria. The cause of these changes might relate to the reduction of membrane fluidity in hepatocellular mitochondria by cold stress.