中文摘要：

于2007年2月，把40尾南方鲇1龄幼鱼分为5个不同的温度处理组，用流水式呼吸仪测定每尾实验鱼的静止代谢率（Ms：mgO2／h·kg），随即处死该实验鱼，提取其肝脏线粒体，采用氧电极在与其静止代谢测定相同的温度条件下以琥珀酸为代谢底物测定其线粒体的代谢耗氧率。在12．5、17．5、22．5、27．5和32．5℃条件下，静止代谢率的值分别为26．64、49．03、73．64、102．40、156．72mgO2／h·kg，单位线粒体蛋白重量的线粒体耗氧率（Mp）分别为12．24、11．76、16．28、21．56和31．43nmolO2／min·mg，单位组织重量的线粒体耗氧率（Mt）则分别为64．02、78．72、117．51、121．57和194．20nmolO2／min·g。为了比较南方鲇肝脏离体线粒体的底物偏好性，在27．5℃条件下还测定了其以丙酮酸＋苹果酸为底物时的耗氧率。结果显示：该种鱼肝脏离体线粒体对琥珀酸的氧化代谢能力显著高于丙酮酸＋苹果酸（P〈0．05）；在实验温度范围内，鱼体的Ms、Mp和Mt值分别与温度（T：℃）之间呈显著的双对数直线相关，协方差分析表明，鱼体静止代谢率与线粒体代谢率回归方程的斜率（温度指数b）差异显著（P〈0．05），即鱼体静止代谢率与线粒体代谢率随温度变化的趋势不一致。经过计算发现：在最低实验温度条件下（12．5℃）肝器官线粒体代谢总耗氧率占鱼体静止代谢总耗氧率的比例显著高于其他温度梯度（P〈0．05）。通过讨论认为：在低温条件下，肝脏线粒体代谢水平随温度下降速率的减小是该种鱼抵抗低温的适应性调节机制。

英文摘要：

The effects of water temperature on the resting metablolic rate （Ms： mg O2/h-kg） of the southern catfish （Silurus meridionalis Chen） and on the metabolic rate of its liver mitochondria were approached in this study. In February, 2007, 40 oneyear-old juveniles of the southern catfish were divided into 5 groups for different temperature-treatments. The resting metablolic rate of each fish was measured by a continuous-flow respirometer. Then, the fish was killed and the oxygen consumption rate of mitochondria isolated from the liver of this tested fish was determined using an oxygen electrode with succinate as metabolic substrate, at the same temperature as in its resting metabolism measurement. At the temperatures of 12.5, 17.5, 22.5, 27.5 and 32.5℃, the resting metablolic rates of the southern catfish were 26.64, 49.03, 73.64, 102.40, 156.72mg O2/h· kg, while the rates of oxygen consumption by the liver mitochondria per mg of mitochondrial protein （Mp） were 12.24, 11.76, 16.28, 21.56 and 31.43nmol O2/min·mg, and the rates per g of liver tissue （Mt） were 64.02, 78.72, 117.51, 121.57 and 194.20 nmol O2/min·g, respectively. In order to test the substrate preferences of the mitochondria isolated from the liver of the southern catfish, the oxygen consumption rate of the liver mitochondria with pyruvate ＋ malate as metabolic substrate was determined at 27.5 ℃. The results showed that the rate of pyruvate ＋ malate oxidation was significantly lower than the rate of succinate oxidation （p 〈 0.05） . In other words, the mitochodria isolated from the liver of possessed higher capacity for oxidation of succinate. Ms, Mp and Mt all increased with increasing temperature within the range of experimental temperature. There were double-logarithmic linear correlations significantly between the three kinds of metabolic rates and temperature （T： ℃ ）, respectively. The covariance analysis showed that the slope （temperature exponents b） in the equation for Ms was significantly higher than t