Fig. 3. Profiling of receptors responsible for cytosolic Ca²⁺ responses. (A) Ca²⁺ signals recorded from fura 2-loaded neurospheres evoked by a variety of P2-receptors agonists. Whereas all P2Y₁-receptor agonists (ATP, 2-MeSATP, ADPßS, 2-ClATP, 2-MeSADP) induced a comparable response, the P2X receptor agonists ,ß-meATP, ß,-meATP and BzATP, the P2Y₁₄ receptor agonist UDP-glucose, and the P1-receptor agonist adenosine were ineffective (50 µM each). Ca²⁺ signals were normalized to the ATP response (100%) obtained in the identical neurosphere. (B) Independence of the cytosolic Ca²⁺ response on extracellular Ca²⁺ (e-Ca²⁺) following application of ATP (50 µM). (C) Dependence of the cytosolic Ca²⁺ response on intracellular Ca²⁺. Pre-application for 10 minutes of the Ca²⁺ store blocker thapsigargin (Th, 5 µM) strongly diminished the Ca²⁺ elevations evoked by ATP or ADP (50 µM each). Responses were normalized to the ATP (or ADP) response (100%) obtained in the identical neurosphere (mean±s.d., n=5-19 (A), 27 (B) or 7-9 (C); ^*P<0.05, ^**P<0.01).