Transport of 2-deoxy-D-[3H]glucose in microvessels isolated from bovine cerebral cortex

Abstract

Microvessels were isolated from a bovine cortex and the transport of glucose was investigated by using 2-deoxy-D-[3H]glucose (2-DG). The apparent Km for 2-DG transport was 118 microM and therefore indicates a significant high affinity for the substrate. The inhibition of 2-DG uptake by D-glucose showed an apparent Ki of 222 microM. Other sugars, e.g., 3-methyl-D glucose and D-fructose, also inhibited the 2-DG uptake by 60.6 and 36.0%, respectively. Phloretin (1 X 10(-3) M) inhibited the 2-DG transport more than phlorizin (83.7 vs. 53.8%). Ouabain (1 and 5 X 10(-4) M) did not inhibit the uptake of 2-DG but 2,4-dinitrophenol (1 X 10(-4) M) did (78.0%). The uptake of 2-DG could not be demonstrated in homogenized microvessels. Adenine nucleotides (conc. 2 mM) had various effects on the 2-DG uptake by microvessels. ATP inhibited the uptake by 20.7%, ADP was virtually without effect, and AMP stimulated the uptake of 2-DG by 8.5%. It was also found that the decrease of adenylate energy charge favors the uptake of 2-DG. All these findings suggest that, in cerebral microvessels of a bovine cortex, 2-DG is apparently transported by a specific, carrier-mediated transport system.