Patrini C, Reggiani C, Laforenza U, Rindi G
Institute of Human Physiology, University of Pavia, Italy.
J Neurochem. 1988 Jan;50(1):90-3. doi: 10.1111/j.1471-4159.1988.tb13234.x.
To calculate the kinetic parameters of thiamine monophosphate transport across the rat blood-brain barrier in vivo, different doses of a [35S]thiamine monophosphate preparation with a specific activity of 14.8 mCi.mmol-1 were injected in the femoral vein and the radioactivity was measured in arterial femoral blood and in the cerebellum, cerebral cortex, pons, and medulla 20 s after the injection. This short experimental time was used to prevent thiamine monophosphate hydrolysis. Thiamine monophosphate was transported into the nervous tissue by a saturable mechanism. The maximal transport rate (Jmax) and the half-saturation concentration (Km) equaled 27-39 pmol.g-1.min-1 and 2.6-4.8 microM, respectively. When compared with that of thiamine, thiamine monophosphate transport seemed to be characterized by a lower affinity and a lower maximal influx rate. At physiological plasma concentrations, thiamine monophosphate transport rate ranged from 2.06 to 4.90 pmol.g-1.min-1, thus representing a significant component of thiamine supply to nervous tissue.
为了计算硫胺素单磷酸酯在大鼠体内血脑屏障的转运动力学参数，将比活度为14.8 mCi·mmol⁻¹的不同剂量[³⁵S]硫胺素单磷酸酯制剂注入股静脉，并在注射后20秒测量股动脉血以及小脑、大脑皮层、脑桥和延髓中的放射性。采用这个较短的实验时间是为了防止硫胺素单磷酸酯水解。硫胺素单磷酸酯通过一种可饱和机制转运到神经组织中。最大转运速率（Jmax）和半饱和浓度（Km）分别为27 - 39 pmol·g⁻¹·min⁻¹和2.6 - 4.8 μM。与硫胺素相比，硫胺素单磷酸酯的转运似乎具有较低的亲和力和较低的最大流入速率。在生理血浆浓度下，硫胺素单磷酸酯的转运速率范围为2.06至4.90 pmol·g⁻¹·min⁻¹，因此是向神经组织供应硫胺素的一个重要组成部分。
