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Blood–Brain Transport of Thiamine Monophosphate in the Rat: A Kinetic Study In Vivo
Author(s) -
Patnni Cesare,
Reggiani Carlo,
Laforenza Umberto,
Rindi Gianguido
Publication year - 1988
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1988.tb13234.x
Subject(s) - in vivo , thiamine , chemistry , biochemistry , neuroscience , biology , genetics
To calculate the kinetic parameters of thiamine monophosphate transport across the rat blood‐brain barrier in vivo, different doses of a [ 35 S]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 ( J max ) and the half‐saturation concentration ( K m ) equaled 27–39 pmol·g −1 ·min −1 and 2.6–4.8 μ M , 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.