Figure A3.

Fit of contraction data of guinea‐pig ileum through activation of muscarinic receptors with carbachol (filled blue diamonds) and oxotremorine (open red circles) in normal tissue (darker colors) and in the same tissue after controlled alkylation of the muscarinic receptor with 1 mmol/L phenoxy‐benzamine for 10 h followed by 2 h drug‐free wash (lighter colors). Data after (Kenakin and Christopoulos 2011) were fitted both with the operational model (A, top, eq. 19) and the present model (B, bottom, eq. 31). Fit requires the assumption that oxotremorine has higher receptor‐binding affinity, but lower efficacy than carbachol. Both gave essentially identical fits with a slightly better fit for the present model as judged by the sum of squared errors (SSE of 278 vs. 331) as well as by the Akaike Information Criteria, a more rigorous model selection criteria used to compare models that have different numbers of parameters (Buchwald 2007) (AIC of 143.4 vs. 145.4).