Kainulainen H, Komulainen J, Leinonen A, Rusko H, Vihko V
Department of Cell Biology, University of Jyväskylä, Finland.
Basic Res Cardiol. 1990 Nov-Dec;85(6):630-9. doi: 10.1007/BF01907897.
Male rats, aged 17 weeks at the end of experiments, were divided into four groups. Two groups lived in normal cage conditions with or without extra load (20% of the body weight) and two groups were trained by running with or without extra load for 8 weeks. Oxidation rates of succinate, glutamate + malate, palmitoylcarnitine, and pyruvate, and the activities of lactate dehydrogenase, citrate synthase, isocitrate dehydrogenase and cytochrome oxidase were measured in homogenates of the right ventricle and in those of the subendocardial and subepicardial layers of the left ventricle. Oxidation rates of succinate and palmitoylcarnitine tended to be higher in the subendocardium than in the subepicardium of sedentary control animals (p less than 0.1 and p less than 0.05, respectively). Transmural differences of succinate and palmitoylcarnitine oxidation rates were even more clear after running training (p less than 0.01 and p less than 0.05, respectively), after carrying extra load (p less than 0.001 and p less than 0.001, respectively) and after training carrying extra load (p less than 0.001 and p less than 0.05, respectively). Training also enhanced pyruvate oxidation rate in the subendocardium. Oxidation rates of all substrates were lower in the right ventricle than in the left ventricle. In control animals there were no regional differences in the myocardial enzyme activities and the training- or extra-load-induced changes were modest compared with the changes in the oxidation rates. The most significant change was the training-induced enhancement in the lactate dehydrogenase activity of the subendocardium (p less than 0.001 vs subepicardium). These results show greater subendocardial than subepicardial oxidation rates of certain substrates in the normal heart. These results also suggest that the myocardium adapts to increased work by increasing the subendocardial oxidation rate of some but not all substrates, indicating further that there may be qualitative mitochondrial differences in the different regions of the heart.
实验结束时年龄为17周的雄性大鼠被分为四组。两组在正常笼养条件下生活，一组有额外负荷（体重的20%），另一组没有；另外两组进行跑步训练，一组有额外负荷，另一组没有，训练为期8周。在右心室以及左心室内膜下层和心外膜下层的匀浆中测量了琥珀酸、谷氨酸+苹果酸、棕榈酰肉碱和丙酮酸的氧化速率，以及乳酸脱氢酶、柠檬酸合酶、异柠檬酸脱氢酶和细胞色素氧化酶的活性。在久坐不动的对照动物中，内膜下层的琥珀酸和棕榈酰肉碱氧化速率往往高于心外膜下层（分别为p<0.1和p<0.05）。跑步训练后（分别为p<0.01和p<0.05）、负重后（分别为p<0.001和p<0.001）以及负重训练后（分别为p<0.001和p<0.05），琥珀酸和棕榈酰肉碱氧化速率的跨壁差异更加明显。训练还提高了内膜下层的丙酮酸氧化速率。所有底物的氧化速率在右心室中均低于左心室。在对照动物中，心肌酶活性没有区域差异，与氧化速率的变化相比，训练或额外负荷引起的变化较小。最显著的变化是训练导致内膜下层的乳酸脱氢酶活性增强（与心外膜下层相比，p<0.001）。这些结果表明，在正常心脏中，某些底物的内膜下层氧化速率高于心外膜下层。这些结果还表明，心肌通过增加部分而非全部底物的内膜下层氧化速率来适应增加的工作量，进一步表明心脏不同区域的线粒体可能存在质的差异。
