Figure 2.

The β₂AR induced calcium response is due to release from the endoplasmic reticulum. a and b, chelation of extracellular Ca²⁺ with EGTA does not eliminate β₂AR-mediated Ca²⁺ mobilization. c, depletion of endoplasmic reticulum Ca²⁺ by treatment with thapsigargin (TG) for 5 min nearly eliminates signaling with ISO. d, treatment with InsP₃R inhibitor 2-APB and PLC inhibitor U73122 for 1 h suppresses signaling with ISO. Ca²⁺ traces represent three or more independent experiments, and error bars indicate internal replicate S.E. AU, absorbance units.