Guezennec C Y, Nonglaton J, Serrurier B, Merino D, Defer G
Centre d'Etudes et de Recherches de Médecine Aérospatiale, Laboratoire Central de Biologie Aérospatiale, Paris, France.
Eur J Appl Physiol Occup Physiol. 1988;57(1):114-9. doi: 10.1007/BF00691249.
Four groups of rats were subjected to the following conditions: (1) 48 h fasting, (2) 48 h of 4 degrees C cold exposure, (3) 5 h treadmill running, (4) 48 h fasting with 4 degrees C cold exposure. The groups were compared to fed control rats in order to study hormonal and metabolic responses in blood and tissue samples. Isolated hepatocytes were used to evaluate the rate of ketogenesis. Decreases in liver glycogen and increases in blood free fatty acids (FFA) confirmed that glycogenolysis and lipolysis occur in these situations of metabolic stress. Increases in the glucagon/insulin plasma ratio were also noted. Plasma catecholamine levels were only enhanced after running and after cold exposure. Production of blood ketone bodies was stimulated more by running and by fasting than by cold exposure. The low ketone body production observed after cold exposure seems to be linked to increases liver glycogen levels and decreased FFA availability. Liver cells isolated after cold exposure exhibited higher ketogenesis than these isolated after running. This difference in ketogenic capacity could result both from the longer hormonal stimulation by high glucagon/insulin plasma ratios and from the metabolic state of the liver.
(1) 禁食48小时；(2) 4℃冷暴露48小时；(3) 跑步机跑步5小时；(4) 禁食48小时并4℃冷暴露。将这些组与喂食对照大鼠进行比较，以研究血液和组织样本中的激素和代谢反应。使用分离的肝细胞评估生酮率。肝糖原减少和血液游离脂肪酸(FFA)增加证实了在这些代谢应激情况下发生了糖原分解和脂肪分解。还注意到血浆胰高血糖素/胰岛素比值增加。血浆儿茶酚胺水平仅在跑步后和冷暴露后升高。跑步和禁食比冷暴露更能刺激血液中酮体的产生。冷暴露后观察到的低酮体产生似乎与肝糖原水平升高和FFA可用性降低有关。冷暴露后分离的肝细胞比跑步后分离的肝细胞表现出更高的生酮作用。这种生酮能力的差异可能是由于高血浆胰高血糖素/胰岛素比值的激素刺激时间更长以及肝脏的代谢状态所致。
