Stimulation of mouse brain gamma-hydroxybutyric acid transport by pyridoxal 5'-phosphate.
A synaptosomal preparation from mouse brain transported gamma-hydroxybutyric acid in a manner displaying saturation kinetics. A Kt of 48 +/- 11 microM was calculated. In the presence of pyridoxal 5'-phosphate, uptake was markedly enhanced. Stimulation of uptake was observed with increasing concentrations of pyridoxal 5'-phosphate, up to a maximum of about 3.5 mM. Increasing concentrations above this value led to a steady decrease in the stimulation of uptake, till at 7 mM pyridoxal 5'-phosphate and above there was a noticeable inhibition of uptake. The presence of increasing concentrations of gamma-hydroxybutyric acid gradually reduced the amount of stimulation, thus pyridoxal 5'-phosphate appeared to be producing its effect by reducing the Kt of the transport system rather than increasing its Vmax.
Tunnicliff
G
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Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Evansville 47712.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D011732:Pyridoxal Phosphate / Q000494:pharmacology*; D012978:Sodium Oxybate / Q000378:metabolism*
D011732:Pyridoxal Phosphate; D012978:Sodium Oxybate