Stereospecific Permeability of Rat Blood‐Brain Barrier to Lactic Acid
Stereospecific Permeability of Rat Blood‐Brain Barrier to Lactic Acid
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大鼠血脑屏障对乳酸的立体定向渗透性
DOI：
10.1161/01.str.5.1.81
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发表时间：
1974
期刊：
影响因子：
8.3
通讯作者：
J. Severinghaus
中科院分区：
文献类型：
--
作者：
Edwin M. Nemato;J. Severinghaus
肝切除大鼠静脉注射14 C和32 P后1、2、5和10分钟测定血和全脑14 C和32 P活性。注射14 C-标记的L-乳酸或D-乳酸和32 P-标记的大鼠红细胞。全脑匀浆14 C校正血液14 C，并化学分配为14 C-乳酸盐、14 CO2和其他14 C化合物。在对照组中，用14 C-D-葡萄糖和125 L-安替比林代替乳酸盐。在注射后1分钟，全脑14 C表示为总注射14 C活性的百分比和安替比林值的百分比为：安替比林1.78%（100%）; D-葡萄糖1.45%（81%）; L-乳酸0.36%（20%）;和D-乳酸0.13%（7%）。注射L-乳酸盐后1分钟，脑14 C为74%乳酸盐、5% CO2和21%其他化合物。用冷的外消旋乳酸钠预负荷大鼠将L-乳酸盐摄取降低至注射液的0.14%（8%安替比林），并将D-乳酸盐摄取降低至0.09%（= 5%安替比林）。在2分钟、5分钟和10分钟时，大脑含有更多的14 C，其中更大的部分代谢为CO2和来自L-乳酸和D-乳酸的其他化合物。血脑屏障似乎含有可饱和的乳酸载体，其表现出三倍的L-立体特异性至D-立体特异性，但导致比可比的葡萄糖载体少得多的净转运。在正常血液pH值下，乳酸盐转运可能受到中性乳酸缺乏的限制。
Blood and whole brain 14C and 32P activities were determined in hepatectomized rats one, two, five and ten minutes after intravenous (I.V.) injection of 14C-labeled L-lactate or D-lactate and 32P-labeled rat red blood cells. Whole brain homogenate 14C was corrected for blood 14C and chemically partitioned into 14C-lactate, 14CO2 and other 14C compounds. In controls, lactate was replaced with 14C-D-glucose and 125l-antipyrine. At one minute postinjection, whole brain 14C expressed as percent of total injected 14C activity and as percent of the antipyrine value were: antipyrine 1.78% (100%); D-glucose 1.45% (81%); L-lactate 0.36% (20%); and D-lactate 0.13% (7%). One minute after L-lactate injection, brain 14C was 74% lactate, 5% CO2 and 21% other compounds. Preloading rats with cold racemic Na-lactate reduced L-lactate uptake to 0.14% of the injectate (8% of antipyrine), and reduced D-Iactate uptake to 0.09% (= 5% of antipyrine). At two, five and ten minutes, brain contained more 14C with larger fractions metabolized to CO2 and other compounds from both L-lactate and D-lactate. The blood-brain barrier appears to contain a saturable lactate carrier exhibiting threefold L-stereospecificity to D-stereospecificity, but resulting in far less net transport than the comparable glucose carrier. Lactate transport may be limited by the scarcity of neutral lactic acid at normal blood pH.