We used a linear mixed model to fit the different current-density curves and correct for repeated measurments per well as well as random effects from the two experiments. Then we contrasted per voltage step the difference between cell types. General model design:
value ~ as.factor(V_Clamp)*Celltypes + (1|Plate_ID/Well)
Fixed effects
Main effect of as.factor(V_Clamp): - These are the baseline IV curve for Celltype1. You see strong significance (p < 0.001) across many clamp steps — expected, since current increases with depolarization.
Main effect of Celltypes: The coefficient for Celltype2 (at reference clamp step, here -70 mV) tells you the offset between cell types at baseline. Often not significant — which is fine, because the real differences may only appear at depolarized steps.
Interaction terms: These are key. A significant interaction (as.factor(V_Clamp)*Celltypes) means the IV curve shape differs between cell types.
For example, in your CD.peak model, the interaction is significant around +10 and +20 mV (p ~ 0.03). That suggests cell type differences emerge in the depolarized range.
In CD.iss and CD.tail models, you see significance at positive voltages too, with some consistent directional effects.
So the story is: the two cell types don’t differ much at hyperpolarized potentials, but diverge at depolarized voltages.