Cerebral metabolism during cord occlusion and hypoxia in the fetal sheep: a novel method of continuous measurement based on heat production.
Cerebral metabolism during cord occlusion and hypoxia in the fetal sheep: a novel method of continuous measurement based on heat production.
复制标题
胎羊脐带闭塞和缺氧期间的大脑代谢：一种基于产热的连续测量的新方法。
DOI：
10.1113/jphysiol.2003.048082
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Power,GordonG
中科院分区：
文献类型：
--
作者：
Hunter,ChristianJ;Blood,ArlinB;Power,GordonG
这项研究是为了验证一种新的方法来测量胚胎绵羊的大脑代谢率，该方法基于大脑局部区域的热产生。比较了20个近月胎儿在基础状态、中度缺氧和脐带闭塞时的产热和耗氧量。放置热电偶测量核心和大脑温度，将复合探头放置在顶叶皮质，使用激光多普勒血流仪测量皮质血流量(CBF)的变化，并使用荧光衰减法测量组织PO2的变化。将导管插入头臂动脉和矢状窦进行采血。在中度低氧条件下，给绵羊灌服10−12%氧气后，胎儿动脉血氧分压从23±1降至11±1托，脑组织氧分压从7·6±0·7降至0·8±0·4托的最低点，脑血流量增加至基线的139±5%。皮质热产生(计算为CBF、从动脉到脑组织的温度增益和血液比热的乘积)减少了45%±11%，与摄氧量的下降类似。脐带完全阻断10min后，胎儿动脉血氧分压(PO2)由23±1降至9±2托，脑组织氧分压(PO2)由7.0±0.7降至基本为0，脑血流量下降40±5%。皮质产热率下降78±6%，氧耗量下降90±3%。相对于氧气使用，葡萄糖摄取量显着增加，矢状窦血液中乳酸浓度增加。我们的结论是，局部测量大脑中的热产生提供了一个有用的总体代谢率指数，密切地反映了中度缺氧时的氧气使用情况，并表明在严重窒息期间无氧代谢的显著贡献。
This study was undertaken to validate a new method of measuring cerebral metabolic rate in the fetal sheep based on heat production in a local region of the brain. Heat production was compared to oxygen use in 20 near‐term fetuses during basal conditions, moderate hypoxia and cord occlusion. Thermocouples were placed to measure core and brain temperature and a composite probe placed in the parietal cortex to measure changes in cortical blood flow (CBF) using laser Doppler flowmetry and tissuePO2using fluorescent decay. Catheters were inserted in a brachiocephalic artery and sagittal sinus for blood sampling. With moderate hypoxia, induced by administering 10−12 % oxygen to the ewes, fetal arterialPO2declined from 23 ± 1 to 11 ± 1 Torr and brain tissuePO2fell from 7.6± 0.7 to a nadir of 0.8 ± 0.4 Torr, while CBF increased to 139 ± 5 % of baseline. Cortical heat production, calculated as the product of CBF, the temperature gain from artery to brain tissue, and the specific heat of blood, decreased by 45 ± 11 % in parallel to similar declines in oxygen uptake. With severe asphyxia induced by complete cord occlusion for 10 min, fetal arterialPO2declined from 23 ± 1 to 9 ± 2 Torr and brain tissuePO2fell from 7.0 ± 0.7 to essentially 0 Torr while CBF decreased 40 ± 5 %. Cortical heat production decreased by 78 ± 6 % while oxygen use declined by 90 ± 3 %. Glucose uptake increased significantly relative to oxygen use and lactate concentration increased in sagittal sinus blood. We conclude that local measurements of heat production in the brain provide a useful index of overall metabolic rate, closely reflecting oxygen use in moderate hypoxia and indicating a significant contribution from anaerobic metabolism during severe asphyxia.