Blomqvist G, Thorell J O, Ingvar M, Grill V, Widén L, Stone-Elander S
Department of Clinical Neuroscience, Karolinska Pharmacy, Stockholm, Sweden.
Am J Physiol. 1995 Nov;269(5 Pt 1):E948-59. doi: 10.1152/ajpendo.1995.269.5.E948.
A method for determining regional cerebral utilization of ketone bodies in humans is described. After a bolus injection of R-beta-[1-11C]hydroxybutyrate, the time course of the tracer in the brain was measured with positron emission tomography in five healthy volunteers. The regional cerebral blood flow was measured separately. The tracer uptake in the brain could be well described by a single rate constant, indicating that the concentration of unmetabolized ketone bodies in the brain is very low and that transport across the blood-brain barrier is the rate-limiting step. At an average plasma concentration of beta-hydroxybutyrate of 0.043 mumol/ml, the utilization rate was estimated to be 0.48 nmol.ml-1.min-1. In accordance with previous animal studies, the utilization rate was found to increase almost linearly with increasing plasma concentration of beta-hydroxybutyrate. Furthermore, the utilization was higher in gray than in white matter. Finally, the ratio between the utilization in the basal ganglia and the brain as a whole was lower for ketone bodies than for glucose.
本文描述了一种测定人体大脑中酮体区域利用率的方法。对5名健康志愿者静脉注射R-β-[1-¹¹C]羟基丁酸后，用正电子发射断层扫描测量示踪剂在大脑中的时间进程。同时单独测量区域脑血流量。大脑中示踪剂的摄取可用单一速率常数很好地描述，这表明大脑中未代谢酮体的浓度非常低，且跨血脑屏障的转运是限速步骤。在β-羟基丁酸的平均血浆浓度为0.043μmol/ml时，利用率估计为0.48nmol·ml⁻¹·min⁻¹。与先前的动物研究一致，发现利用率几乎随β-羟基丁酸血浆浓度的增加呈线性增加。此外，灰质中的利用率高于白质。最后，与葡萄糖相比，基底神经节与整个大脑的酮体利用率之比更低。
