KINETICS OF ADENOSINE UPTAKE INTO ASTROCYTES

Abstract— Kinetics for uptake of adenosine, a putative inhibitory transmitter, were measured in normal, i.e. non-transformed, astrocytes in cultures obtained from the dissociated, cortex-enriched superficial parts of the brain hemispheres of newborn DBA mice. The uptake kinetics indicated a minor, unsaturable component together with a rather intense (V_max 0.36nmol/min per mg protein) high affinity ( K _m 3.4 μ m ) uptake following Michaelis-Menten kinetics and inhibited by 100 μ m -papaverine. The V_max was about two times higher than that reported in the literature for brain slices suggesting that a considerable part of the adenosine uptake in brain slices occurs into glial cells. Such an accumulation of adenosine into normal astrocytes may play a major role in nucleoside and nucleotide metabolism in the brain and help in regulating the extracellular adenosine concentration.