Figure 1.

Distribution of residuals in Ca²⁺ responses in individual cells is more homogeneous if grouping is performed based on the response level rather than agonist concentration

(A) A representative trace of the responses of an individual HEK293 cell to repeated acetylcholine (Ach) stimulations. Gray shows the repeats of the same concentrations; red lines mark the moments of agonist injection.

(B) Distribution of the response residuals by the average response height. Each of the 362 × 7 × 5 dots represents the residual value plotted against the average value for each of the 362 cells tested 7 times at 5 different Ach concentrations.

(C) Pooled distributions of the residuals obtained for a particular concentration at high (10 μM) and lower (500 and 250 nM) concentrations demonstrate significant asymmetries at the lower concentrations.