ROLE OF CA IN THE REGULATION OF ENERGY METABOLISM

该项目旨在评估 钙离子在能量代谢调节中的作用。 具体来说，我们有 将分离的心肌细胞暴露于各种预期 改变胞质游离钙离子浓度， 丙酮酸脱氢酶（[PDHA]）的活性形式， 以及用荧光螯合来估计钙浓度 剂. 方案包括进行性质膜去极化 随着KCl的增加，以及使用藜芦碱。 此外，我们还使用 在细胞上强制quiscence的干预，即加载 螯合剂和使用抑制剂ryanodine，以分离 钙对丙酮酸脱氢酶的影响从减少 ATP/ADP比率，这通常是钙增加的结果 肌肉的可用性。 这些研究表明，钙是 定量控制丙酮酸脱氢酶的重要信号 心脏细胞的活动。 我们还研究了钙在控制丙酮酸中的作用 脱氢酶。 胰高血糖素加压素 和α 1肾上腺素能激动剂苯肾上腺素都导致了 胞浆游离钙浓度，PDHA含量增加， 线粒体NADH含量增加：后者表明 线粒体脱氢酶活性普遍增加。 此外，本发明还 佛波醇酯，激活蛋白激酶C，被发现可以防止 由于胰高血糖素或苯丙氨酸引起的钙增加，但不是由于 加压素 在每一种情况下， 胞浆游离钙浓度和PDHA含量的影响，在强 支持的论点，前者行使很大程度的控制 而不是后者。

This project is designed to assess the physiological importance of calcium-ions in the regulation of energy metabolism. Specifically, we have exposed isolated cardiac myocytes to a variety of conditions expected to alter cytosolic free calcium ion concentration and have measured the amount of the active form of pyruvate dehydrogenase ([PDHA]) which results, as well as estimating calcium concentration with fluorescent chelating agents. Protocols have included progressive plasma membrane depolarization with increasing KCl, and the use of veratridine. Further, we have used interventions which enforce quiscence on the cells, viz. loading with chelating agents and the use of the inhibitor ryanodine, to separate the effect of calcium on pyruvate dehydrogenase from the effects of a decrease in the ATP/ADP ratio, which is normally a sequel to increased calcium availability in muscle. These studies have shown that calcium is quantitatively an important signal in controlling pyruvate dehydrogenase activity in heart cells. We have also investigated the role of calcium in the control of pyruvate dehydrogenase in isolated hepatocytes. The hormones glucagon, vasopressin and the alpha1-adrenergic agonist phenylephrine all led to an increase in cytosolic free calcium concentration, an increase in PDHA content and an increase in mitochondrial NADH content: the latter is indicative of increased mitochondrial dehydrogenase activity in general. Further, phorbol esters, which activate protein kinase C, were found to prevent increases in calcium due to glucagon or phenylephrine, but not that due to vasopressin. In every case, there was a parallelism between effects on cytosolic free calcium concentration and effects on PDHA content, in strong support of the thesis that the former exercises a large degree of control over the latter.