Fig. 5.

(A) Inositol phosphate production in human P2Y₆-transfected 1321N1 human astrocytes. (B) Concentration dependence of inhibition by compound MRS2575 (7) of inositol phosphate production induced by UDP (300 nM) in human P2Y₆-receptor transfected 1321N1 human astrocytes. After labeling with myo-[³H]inositol (1 μCi/10⁶ cells) for 24 h, the cells were treated for 30 min at 37 °C with the antagonist or buffer in the presence of LiCl, followed by addition of agonist, UDP, for another 30 min. The quantity of inositol phosphates was analyzed after extraction though Dowex AG 1-X8 columns (see Section 2). Data shown represent the mean ± S.E.M. of three independent experiments in triplicate.