Ezzat S, Pahl-Wostl C, Rudin M, Harris A G
Division of Endocrinology and Metabolism, University of Toronto, Ontario, Canada.
Peptides. 1994;15(7):1223-7. doi: 10.1016/0196-9781(94)90145-7.
NMR spectroscopy is a useful tool for monitoring multiple intermediate metabolic pathways in different organs in intact animals and humans. We report the effect of the somatostatin analogue octreotide on the fate of 13C-labeled glucose administered to fasted and well-fed rats as determined by NMR spectroscopy. The production of 13C-labeled glycogen and its subsequent breakdown after the end of infusion was identified with a time resolution of 7 min. Hepatic glycogen synthesis was not different between control and octreotide-treated animals but persisted for 15 min after the end of the infusion only in control animals. Glycogenolysis, however, was initiated immediately after the end of infusion in octreotide-treated animals where the half-life of glycogen was 40 min compared with 68 min in control animals. However, once initiated, the rate of glycogenolysis was not significantly altered by octreotide. Although octreotide had no effect on glucose signal intensities in fasted animals, 13C glucose signals were more intense in octreotide compared with control well-fed animals. In conclusion, octreotide alters rat hepatic metabolism by accelerating the onset of glycogenolysis and stimulating glucose accumulation without significantly interfering with glycogen synthesis.
核磁共振光谱是监测完整动物和人类不同器官中多种中间代谢途径的有用工具。我们报告了生长抑素类似物奥曲肽对禁食和进食良好的大鼠给予13C标记葡萄糖的代谢命运的影响，该影响通过核磁共振光谱测定。以7分钟的时间分辨率确定了13C标记糖原的产生及其在输注结束后的后续分解。对照动物和奥曲肽处理动物之间的肝糖原合成没有差异，但仅在对照动物中，输注结束后肝糖原合成持续了15分钟。然而，在奥曲肽处理的动物中，输注结束后立即开始糖原分解，其中糖原的半衰期为40分钟，而对照动物为68分钟。然而，一旦开始，奥曲肽对糖原分解速率没有显著影响。尽管奥曲肽对禁食动物的葡萄糖信号强度没有影响，但与对照进食良好的动物相比，奥曲肽处理的动物中13C葡萄糖信号更强。总之，奥曲肽通过加速糖原分解的开始和刺激葡萄糖积累来改变大鼠肝脏代谢，而不会显著干扰糖原合成。
