不同条件下离体大鼠肝脏线粒体能量代谢微量热分析

为了探究线粒体的能量代谢过程，本文以离体大鼠肝脏线粒体为模型，利用多通道、高灵敏度的热活性检测仪TAM Ⅲ，实时监测了不同线粒体浓度、不同底物、不同缓冲液、几种呼吸抑制剂以及Ca²⁺和线粒体渗透转换孔抑制剂CsA存在时线粒体的能量代谢，获得了完整的热功率―时间曲线，并通过计算得到了线粒体能量代谢的热动力学参数。通过分析发现：（1）线粒体浓度越大，代谢越快；（2）直接底物琥珀酸钠使线粒体代谢更快；（3）高浓度Ca²⁺能够刺激线粒体快速产热，且在长期代谢进程中，线粒体渗透转换孔抑制剂CsA并不能改变Ca²⁺造成的影响；（4）不同缓冲液对线粒体代谢的影响基于其组分的不同，缓冲液中含有呼吸底物；（5）呼吸抑制剂都能抑制线粒体的能量代谢，尤其是复合物IV的抑制剂NaN₃，高浓度下使代谢停止。

Microcalorimetric Analysis of Isolated Rat Liver Mitochondrial Metabolism under Different Conditions

Isolated rat liver mitochondria were proposed as a model to monitor real-time heat metabolism.A high-throughput and sensitive thermal activity monitor Ⅲ (TAM Ⅲ) was used to detect the P-t curves of mitochondria under different conditions, including different mitochondrial concentrations, different substrates, different buffers, respiratory inhibitors, Ca²⁺, and CsA.We determined the thermokinetic parameters through calculation.The results showed that:(1) higher concentration of mitochondria led to faster energetic metabolism; (2) when succinate was the direct respiratory substrate, it promoted mitochondrial metabolism, in contrast to the condition when an indirect substrate, pyruvate, was used; (3) high concentration of Ca²⁺(2.5 mmol·L^-1) stimulated mitochondrial metabolism, however CsA, an inhibitor of mitochondrial permeability transition pores, could not reverse the Ca²⁺-induced mitochondrial alteration; (4) mitochondria in various buffers displayed different rates of heat metabolism, because of the different composition of the buffers; (5) mitochondrial metabolism was inhibited by respiratory inhibitors, especially NaN₃, which is an inhibitor of Complex Ⅳ and which completely stopped the mitochondrial heat release.