Metabolic Disposition of Glucose Carbon by Sensory Ganglia of 15‐Day‐old Chicken Embryos, with New Dynamic Models of Carbohydrate Metabolism
Metabolic Disposition of Glucose Carbon by Sensory Ganglia of 15‐Day‐old Chicken Embryos, with New Dynamic Models of Carbohydrate Metabolism
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15 日龄鸡胚胎感觉神经节对葡萄糖碳的代谢处置，以及新的碳水化合物代谢动态模型
DOI：
10.1111/j.1471-4159.1980.tb12508.x
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发表时间：
1980
影响因子：
4.7
通讯作者：
M. Larrabee
中科院分区：
文献类型：
--
作者：
M. Larrabee
摘要：将来自14-16日龄鸡胚腰部区域的背根神经节在37°下在含有[1 - 11 C]葡萄糖或[6 - 11 C]葡萄糖和有时32 Pi的改良麦考伊培养基中孵育。90 μg）。连续测量14 CO2的输出。孵育3-17 h后，测量14 C掺入组织成分和释放到培养基中的产物。在神经节成分的纸色谱图中分辨出的9种放射性成分中，最多的14 C存在于脂质和残留在起源处的材料中。只有脂质和原材料可检测到标记的32 Pi。在应该含有戊糖循环中间体的色谱区域中，仅发现相对少量的来自[6 - 14 C]葡萄糖的14 C。至少有五种标记的产品被释放到沐浴介质中。其中，在乳酸中发现了最大量的14 C。释放的第二种成分，可能是丙氨酸，也接受了相当多的14 C。在培养基中未检测到产物中的~（32）P。葡萄糖摄取速率保持相对恒定，因为在长时间实验期间培养基中的葡萄糖浓度下降近10倍。两种新的葡萄糖代谢动力学模型成功解释了先前报道的[1 - 14 C]葡萄糖、[2 - 14 C]-葡萄糖和[6 - 14 C]葡萄糖的14 CO2输出的时间过程和幅度。这些模型是基于这样一个假设，即葡萄糖碳在代谢链早期的中间体池中以及在柠檬酸循环中或之前的第二个池中延迟到CO2。两种模型都将戊糖循环分配给一个细胞区室，并将缓慢转化的物质掺入另一个细胞区室。根据这两个模型，不超过一半的戊糖循环产生的甘油醛-P转化为果糖-6-P，而至少一半的这种和其他来自戊糖循环的果糖-6-P被再循环到其中。这些结论不同于先前模型的结论，该模型假设葡萄糖碳在与戊糖循环相关的池中延迟：该模型表明戊糖循环产生的甘油醛-P和果糖-6-P都可以完全再循环。根据所有模型，在柠檬酸循环中，回收效率超过80%。所有模型都证明了在葡萄糖的碳1、2和6的代谢处理中可能发生的巨大差异。在描述葡萄糖代谢在不同途径之间的分配时，需要考虑这些差异。
Abstract: Dorsal root ganglia from the lumbar region of chicken embryos 14–16 days old were incubated at 37° in modified McCoy's culture medium containing [l‐11Cjglucose or [6‐11C]glucose and sometimes 32Pi A volume of 10 μl of medium was used for four ganglia (dry weight approx. 90 μg). The output of 14CO2 was measured continuously. Incorporation of 14C into tissue constituents and into products released to the medium was measured after incubation for 3–17 h. Among nine radioactive components resolved in paper chromato‐grams of ganglion constituents, the most 14C was found in lipids and on materials remaining at the origin. Only the lipids and the origin materials were detectably labeled by 32Pi. Only relatively small amounts of 14C from [6‐14C]glucose were found in chromatographic regions that should contain intermediates of the pentose cycle. At least five labeled products were released to the bathing medium. Among these, the largest amount of 14C was found in lactic acid. A second component released, possibly alanine, also received considerable 14C. No 32P was detected in products in the medium. The rate of glucose uptake remained relatively constant as the concentration of glucose in the medium declined nearly 10‐fold during prolonged experiments. Two new dynamic models of glucose metabolism successfully explained the time courses and magnitudes of previously reported 14CO2 outputs from [l‐14C]glucose, [2‐14C]‐glucose, and [6‐14C]glucose. These models are based on the assumption that glucose carbon was delayed on its way to CO2 in a pool of intermediates early in the metabolic chain and in a second pool either in or before the citric acid cycle. Both models assigned the pentose cycle to one cellular compartment, and incorporation into slowly‐turning‐over substances to another cellular compartment. According to both models, not more than one‐half of the glyceraldehyde‐P produced by the pentose cycle was converted to fruc‐tose‐6‐P, while at least half of this and other fructose‐6‐P from the pentose cycle was recycled into it. These conclusions differ from those from a previous model, which assumed that glucose carbon was delayed in a pool related to the pentose cycle: that model had suggested full recycling of both the glyceraldehyde‐P and the fructose‐6‐P produced by the pentose cycle. In the citric acid cycle the efficiency of recycling was over 80%, according to all models. All models demonstrated the large differences that can occur in the metabolic handling of carbons 1, 2, and 6 of glucose. These differences need consideration in any description of the partitioning of glucose metabolism between alternative pathways.