Figure 3.

Relative agonist activity as a function of changing receptor density. Values of log(τ/K_A), pEC₅₀, and log(RA) for two agonists (one designated with a solid line and the other with a dotted line) were calculated for a range of τ values. (A) Because values of log(τ/K_A) do not change with receptor density, the ratio Δlog(τ/K_A) remains constant over all ranges of receptor density. (B and C) The pEC₅₀ values change with receptor density for transducer slope coefficients of ≠1, leading to variance and reversal of ΔpEC₅₀ values with receptor density (or changes in receptor coupling efficiency, K_E). (D and E) Values of log(RA) change with τ values for slope coefficients of ≠1, leading to differences in the value of Δlog(RA) with varying receptor density as simulated by changes in τ.