Kubonoya K, Yoneyama Y, Sawa R, Araki T, Power G G
Department of Obstetrics and Gynecology, Nippon Medical School, Tokyo, Japan.
Pflugers Arch. 1998 Oct;436(5):667-72. doi: 10.1007/s004240050687.
The purpose of this study was to compare core body and brain temperatures after complete but intermittent occlusions of the umbilical cord. Thermocouple probes were placed in the parasagittal parietal cortex, ascending aorta, and jugular vein of eight near-term fetal sheep and in the maternal descending aorta. Three days later, after an initial control period, the umbilical cord was occluded for 5 min, followed by a 30-min recovery period, and this cycle was repeated 4 times. Temperature changes, blood gases, and plasma glucose, lactate and adenosine were measured. In the first occlusion period, body core temperature increased 0.12 degreesC over control, and then declined to baseline after cord release, and this pattern was repeated with subsequent occlusions. Brain temperature, however, did not increase in response to any of the cord occlusions. Plasma adenosine increased 2.4-fold during the first occlusion, but not during subsequent occlusions, despite a continuing pattern of constant brain temperature, a result which minimizes adenosine's importance as a continuing regulator of cerebral metabolism. We conclude that brain temperature fails to increase because of diminished heat production by the brain and increases in cerebral blood flow, responses which delay complete depletion of adenosine 5'-triphosphate stores in brain tissue.
本研究的目的是比较在完全但间歇性阻断脐带后核心体温与脑温的变化。将热电偶探头置于8只近足月胎羊的矢状旁顶叶皮质、升主动脉、颈静脉以及母羊的降主动脉中。三天后，在初始对照期过后，脐带被阻断5分钟，随后是30分钟的恢复期，此循环重复4次。测量温度变化、血气以及血浆葡萄糖、乳酸和腺苷水平。在第一次阻断期，核心体温较对照升高0.12℃，脐带松开后降至基线水平，随后的阻断重复此模式。然而，脑温在任何一次脐带阻断后均未升高。尽管脑温持续保持稳定，但血浆腺苷在第一次阻断时增加了2.4倍，而在随后的阻断中未增加，这一结果使腺苷作为脑代谢持续调节因子的重要性降至最低。我们得出结论，脑温未能升高是因为脑产热减少以及脑血流量增加，这些反应延缓了脑组织中三磷酸腺苷储备的完全耗竭。
