Dahlquist G, Persson B
Pediatr Res. 1976 Nov;10(11):910-7. doi: 10.1203/00006450-197611000-00002.
Cerebral blood flow (CBF) was measured by means of Celabeled microspheres in infant (20-day-old) and adult (3-month-old) rats, anesthetised with Na-5-ethyl-5-(1-methylpropyl)2-thiobarbituric acid. Cerebral arteriovenous differences of acetoacetate, D-beta-hydroxybutyrate, glucose, lactate, and oxygen and brain DNA content were determined in other groups of similarly treated infant and adult animals fed or starved for 48 or 72 hr. The mean CBF values of 0.48+/-0.04 and 0.62+/-0.07 ml/(g X min), +/- SEM, in infant and adult animals, respectively, were not significantly different. CBF was unaffected by starvation. At any given arterial concentration the cerebral arteriovenous difference of acetoacetate was significantly higher in infant than adult rats. The same was true for D-beta-hydroxybutyrate at arterial concentrations above 1 mmol/liter. There was an approximately linear relationship between arterial concentration of acetoacetate and its cerebral arteriovenous difference in both infant and adult rats. A similar relationship was found for D-beta-hydroxybutyrate only in infant animals. In the fed state, the cerebral uptake of glucose and ketone bodies (micromoles per (mg DNA X min)) was not different in infant and adult rats. During starvation, cerebral uptake of ketone bodies expressed as micromoles per (mg DNA X min) was higher in infant than adult rats, indicating a higher rate of utilization of ketone bodies per cell in these animals. For glucose, no such difference was found in either fed or starved groups (Table 3). The average percentage of the total cerebral uptake of substrates (micromoles per min) accounted for by ketone bodies increased in both infant and adult rats during starvation. This percentage value was clearly higher in infant than adult rats during starvation. After 72 hr of starvation the values were 38.8% and 15.2% in infant and adult rats, respectively (Fig. 3). Calculated cerebral metabolic rate for oxygen (CMRO2), assuming complete oxidation of glucose and ketone bodies and expressed as micromoles per (mg DNA X min), was similar in fed and starved rats of both age groups (Table 3), indicating that ketone bodies serve as an alternative substrate for glucose during starvation. Calculated CMRO2 for glucose plus ketone bodies was similar to the measured CMRO2 in adult rats both in the fed and the starved groups. For infant rats, calculated CMRO2 for glucose plus ketone bodies was higher than measured CMRO2, indicating that in this age group a portion of substrate was used for synthesis or storage rather than for complete oxidation.
采用铯标记微球法，在以5-乙基-5-(1-甲基丙基)2-硫代巴比妥酸钠麻醉的幼龄（20日龄）和成年（3月龄）大鼠中测量脑血流量（CBF）。在其他经类似处理、喂食或饥饿48或72小时的幼龄和成年动物组中，测定乙酰乙酸、D-β-羟丁酸、葡萄糖、乳酸、氧气的脑动静脉差值以及脑DNA含量。幼龄和成年动物的平均CBF值分别为0.48±0.04和0.62±0.07 ml/(g·min)（±SEM），两者无显著差异。CBF不受饥饿影响。在任何给定的动脉浓度下，幼龄大鼠乙酰乙酸的脑动静脉差值显著高于成年大鼠。当动脉浓度高于1 mmol/L时，D-β-羟丁酸的情况也是如此。在幼龄和成年大鼠中，乙酰乙酸的动脉浓度与其脑动静脉差值之间均存在近似线性关系。仅在幼龄动物中，D-β-羟丁酸也发现了类似关系。在喂食状态下，幼龄和成年大鼠脑对葡萄糖和酮体的摄取量（微摩尔每（mg DNA·min））没有差异。在饥饿期间，以微摩尔每（mg DNA·min）表示的脑对酮体的摄取量在幼龄大鼠中高于成年大鼠，表明这些动物中每个细胞对酮体的利用率更高。对于葡萄糖，在喂食或饥饿组中均未发现此类差异（表3）。在饥饿期间，幼龄和成年大鼠中酮体占底物总脑摄取量（微摩尔每分钟）的平均百分比均增加。在饥饿期间，该百分比值在幼龄大鼠中明显高于成年大鼠。饥饿72小时后，幼龄和成年大鼠的值分别为38.8%和15.2%（图3）。假设葡萄糖和酮体完全氧化，以微摩尔每（mg DNA·min）表示的计算脑氧代谢率（CMRO2）在两个年龄组的喂食和饥饿大鼠中相似（表3），表明在饥饿期间酮体可作为葡萄糖的替代底物。在成年大鼠的喂食和饥饿组中，计算得到的葡萄糖加酮体的CMRO2与测量的CMRO2相似。对于幼龄大鼠，计算得到的葡萄糖加酮体的CMRO2高于测量的CMRO2，表明在这个年龄组中，一部分底物用于合成或储存而非完全氧化。
