Morgan H E, Chua B H, Fuller E O, Siehl D
Am J Physiol. 1980 May;238(5):E431-42. doi: 10.1152/ajpendo.1980.238.5.E431.
Cardiac work increased protein synthesis in hearts supplied glucose (mixture 1), glucose-insulin-glucagon-lactate-beta-hydroxybutyrate (mixture 2) or palmitate-beta-hydroxybutyrate-glucose (mixture 3). In hearts provided mixture 1, acceleration of synthesis involved increased rates of peptide chain initiation. In these hearts intracellular concentrations of 5 amino acids decreased and 13 others were unchanged, indicating that faster protein synthesis did not depend on increased amino acid availability. In hearts supplied mixtures 2, 3, or 4 (lactate-glucose-insulin), intracellular concentrations of branched-chain amino acids were decreased by work, whereas intracellular levels of some acidic and neutral amino acids increased. Protein degradation was decreased by work in hearts supplied mixtures 1 and 2, but not mixtures 3 and 4. In hearts provided mixture 1, nitrogen balance was negative, but less so in working preparations. Nitrogen balance was zero or positive in working hearts provided mixtures 2 and 4. These studies indicated that in hearts supplied some, but not all, of the substrate mixtures, cardiac work maintained efficiently of protein synthesis and inhibited protein degradation. An improved method for perfusion of working hearts with albumin-containing buffer is described.
心脏工作增加了接受葡萄糖（混合物1）、葡萄糖 - 胰岛素 - 胰高血糖素 - 乳酸 - β - 羟基丁酸（混合物2）或棕榈酸 - β - 羟基丁酸 - 葡萄糖（混合物3）的心脏中的蛋白质合成。在接受混合物1的心脏中，合成加速涉及肽链起始速率的增加。在这些心脏中，5种氨基酸的细胞内浓度降低，另外13种保持不变，这表明更快的蛋白质合成并不依赖于氨基酸可用性的增加。在接受混合物2、3或4（乳酸 - 葡萄糖 - 胰岛素）的心脏中，工作使支链氨基酸的细胞内浓度降低，而一些酸性和中性氨基酸的细胞内水平升高。在接受混合物1和2的心脏中，工作使蛋白质降解减少，但在接受混合物3和4的心脏中则不然。在接受混合物1的心脏中，氮平衡为负，但在工作的制剂中负值较小。在接受混合物2和4的工作心脏中，氮平衡为零或正。这些研究表明，在接受部分而非全部底物混合物的心脏中，心脏工作维持了蛋白质合成的效率并抑制了蛋白质降解。本文描述了一种用含白蛋白缓冲液灌注工作心脏的改进方法。
