Ca²⁺ signaling in PDCs in response to various P2Y receptor agonists. Ca²⁺ ion transients in freshly isolated PDCs exposed to ATP, ADP, UTP, UDP, UDP-glucose, and the P2Y₁₁ agonist AR-C67085 were analyzed by flow cytometry. After establishing a baseline for 10 seconds, nucleotides were added at the indicated concentrations. Note: Only for UDP, the concentration was titrated down to 0.01 μM. Data were normalized to the peak calcium signal induced by a standard dose of ionomycin (arbitrarily set to 1.0). Representative data of 4 different experiments are shown.