Abstract
Isolated bovine brain microvessels were used as in vitro model of blood/brain barrier. In a phosphate-free Krebs Ringer medium at 37°C, (8-14C)hypoxanthine is taken up by the microvessels and converted for about 45% in the corresponding nucleotide. The initial rate of the uptake is a hyperbolic function of hypoxanthine concentration in the suspending medium. Inorganic phosphate (up to 10 mM) decreases the apparent Km without affecting the apparent Vmax of hypoxanthine uptake. The presence of inorganic phosphate, which (in the absence of hypoxanthine) causes a raise in the ATP concentration in the endothelial cells, induces also an increase in the equilibrium levels of IMP and hypoxanthine within the cells, the value of the nucleotide/base ratio remaining approximately constant.
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Cardelli-Cangiano, P., Fiori, A., Giacomello, A. et al. HYPOXANTHINE UPTAKE BY ISOLATED BRAIN MICRO-VESSELS: 27. Pediatr Res 19, 748 (1985). https://doi.org/10.1203/00006450-198507000-00047
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DOI: https://doi.org/10.1203/00006450-198507000-00047