Figure 6.

Paracrine purinergic signaling after tissue-level injury. ATP and ADP release and diffusion from point (left), linear (middle), and half-field (right) source injuries (A) were numerically simulated, and contributions of ATP and ADP (B) or ADP alone (C) to expected response probabilities P_E were determined for varying number of injured cells in the presence (red) or absence (black) of extracellular ATP and ADP degradation. Simulation parameters: k_ATP = 0 (degradation absent) or 0.05 min⁻¹ (degradation present), k_ADP = 0.25k_ATP, d₀ = 100 nm, τ_1/2 = 15 s. To see this figure in color, go online.