Conversion of Model Parameters with Model Switching
There are certain relations between the parameters of compartment models with different complexity. Accordingly, PKIN can be configured to convert the rate constants when switching between compartment models. This mode is mainly useful when developing from a simple model towards a more complex one. Conversion is enabled with the Model conversion check in the Extras pane.
Behavior if the user switches the model between different compartment models:
- Model conversion disabled: the first time a model is selected, its default values are used, and thereafter the most recent set of parameter values of that particular model. This behavior works on a per-region bases.
- Model conversion enabled: Each time, the user switches between the models, the parameters are converted. If switching is between models with the same number of compartments, the conversion is exact. If the number of compartments is decreased, the lumped parameters of the reduced model are calculated. If the number of compartments is increased, the same values are used for corresponding parameters, and the additional parameters set to the default values. The consequence of this functionality is that when switching the model from 1-tissue to 2-tissue and then back, the K1 and k2 values will be different due to this conversion process.
The conversion is also meaningful for reference tissue models which rely on k2' as an input parameter. The conversion will try to maintain k2' when switching between reference models with explicit k2'.