Peuhkurinen K J
J Mol Cell Cardiol. 1984 Jun;16(6):487-95. doi: 10.1016/s0022-2828(84)80637-9.
The anaplerotic mechanisms are mainly responsible for the intricate control of the size of the total tricarboxylic acid cycle pool, since cataplerotic fluxes leading out of the cycle can even increase during net synthesis of the cycle intermediates. Pyruvate carboxylation is probably the most important anaplerotic mechanism regulating the pool size of the citric acid cycle. However, not much is known of the regulation of pyruvate carboxylation or other ana- or cataplerotic mechanisms, and further research in this area is needed. The evidence accumulated so far indicates that regulation of the tricarboxylic acid cycle pool size serves to optimize energy transduction in heart muscle. This is seen at the level of the tricarboxylic acid cycle, where the tricarboxylic acid cycle intermediates can be taken to act in a catalytic manner to adjust the activities of the individual enzymes of the cycle at an appropriate level for a certain metabolic situation. On the other hand, increase in the mitochondrial citrate content serves as the mediator between the mitochondrial and cytosolic spaces and leads to diminished glucose utilization in glycolysis due to feed-back inhibition. However, net anaplerosis does not constitute a major energy-releasing system in the ischemic myocardium.
回补机制主要负责对三羧酸循环总库大小进行精细调控，因为即便在循环中间产物净合成期间，导致循环流出的分解代谢通量也可能增加。丙酮酸羧化作用可能是调节柠檬酸循环库大小的最重要的回补机制。然而，对于丙酮酸羧化作用或其他回补或分解代谢机制的调控，人们了解得并不多，因此该领域需要进一步研究。目前积累的证据表明，三羧酸循环库大小的调控有助于优化心肌中的能量转导。这在三羧酸循环层面可见一斑，三羧酸循环中间产物可起到催化作用，将循环中各个酶的活性调节至适合特定代谢状况的适当水平。另一方面，线粒体柠檬酸含量的增加充当线粒体和细胞质空间之间的介质，并由于反馈抑制作用导致糖酵解中葡萄糖利用率降低。然而，净回补在缺血心肌中并非主要的能量释放系统。
