Fig. 2.

P2X1 receptor desensitization inhibits Ca ²⁺ entry through P2X1 channels induced by a range of cross-linker IgG F(ab′) ₂ antibody concentrations. Representative Ca ²⁺ responses ( A–E ) and individual Δ[Ca ²⁺ ]i values ( F ) measured in Fura-2-loaded platelet suspensions. ( A ) Ca ²⁺ responses obtained when a range of IgG F(ab′) ₂ concentrations were added to platelet suspensions which contained mAb IV.3 (1 μg/mL). ( B–E ) The effect of pretreatment of platelet suspensions with 600 nM α,β-meATP for 90 seconds on Ca ²⁺ entry following addition of different IgG F(ab′) ₂ concentrations. ( F ) Comparison of peak [Ca ²⁺ ] _i increases following cross-linking of mAb IV.3 with IgG F(ab′) ₂ concentrations, with and without 600 nM α,β-meATP pretreatment.