Chao C R, Hohimer A R, Bissonnette J M
Department of Obstetrics and Gynecology, Oregon Health Sciences University, Portland 97201.
J Cereb Blood Flow Metab. 1989 Feb;9(1):53-7. doi: 10.1038/jcbfm.1989.7.
The effect of cephalic hypotension on brain metabolism was studied in 10 unanesthetized, normoxic (PaO2 greater than 17 mm Hg), late-gestation fetal lambs. Perfusion pressure (cephalic arterial minus sagittal venous pressure) was 40 +/- 1 mm Hg (SEM) during control and was reduced to 10 +/- 1 by occlusion of the Grachio-cephalic artery. Cerebral blood flow was measured with microspheres, and arterial and sagittal vein blood samples were analyzed for oxygen content, glucose, and lactate. During the occlusion, oxygen consumption decreased from 125 +/- 8 to 95 +/- 4 (p less than 0.05) (all values mumol 100 g-1 min-1), and glucose uptake increased from 20 +/- 3 to 25 +/- 1 (p less than 0.05). During the control period, there was no net lactate flux; during the occlusion, lactate excretion was 5.7 +/- 1.4 (p less than 0.005). The control glucose and oxygen uptakes demonstrated a normal 6:1 molar ratio; however, during the occlusion, 9.4 mumol 100 g-1 glucose min-1 were taken up in excess of expected aerobic glucose metabolism. If all of this glucose were anaerobically metabolized to lactate, three times the measured efflux would be produced. The transport properties of the fetal blood-brain barrier may be important factors in perinatal brain injury.
在10只未麻醉、常氧（动脉血氧分压大于17 mmHg）、妊娠晚期的胎羊中研究了头部低血压对脑代谢的影响。对照期间灌注压（头动脉减去矢状静脉压）为40±1 mmHg（标准误），通过阻断头臂动脉将其降至10±1 mmHg。用微球测量脑血流量，并分析动脉血和矢状静脉血样本中的氧含量、葡萄糖和乳酸。阻断期间，氧耗量从125±8降至95±4（p<0.05）（所有数值均为μmol 100 g-1 min-1），葡萄糖摄取量从20±3增至25±1（p<0.05）。对照期无净乳酸通量；阻断期间，乳酸排出量为5.7±1.4（p<0.005）。对照时葡萄糖和氧摄取量呈现正常的6:1摩尔比；然而，阻断期间，每100 g脑组织每分钟摄取的葡萄糖量比预期的有氧葡萄糖代谢量多出9.4 μmol。如果所有这些葡萄糖都无氧代谢为乳酸，产生的乳酸量将是测得的流出量的三倍。胎儿血脑屏障的转运特性可能是围产期脑损伤的重要因素。
