SUBSTRATE-STIMULATED OXYGEN-CONSUMPTION BY ISOLATED RAT-BRAIN MICROVESSELS IN THE PRESENCE AND ABSENCE OF ATP

We report here properties of isolated brain microvessels such as the rate of oxygen consumption with different substrates; the permeabilizing effect of added ATP is studied. With the isolation procedure presented the cerebral endothelium has a metabolic activity comparable to that reported in the literature. The respiratory rate of the microvessels is not affected by the addition of ATP, whereas it is significantly increased by addition of succinate and alpha-chetoglutarate. The exposure of the isolated brain capillaries to ATP, in a Ca2+-free medium, increases the uptake of 6-carboxyfluorescein. This may be due to pores opened by ATP in the endothelial cell membrane in the absence of divalent cations.