Analysis of models for determining intestinal wall permeabilities

Area of Science:

• Pharmacology
• Physiology
• Biomedical Engineering

Background:

• Mass transport models are essential for analyzing intestinal wall permeability in perfusion experiments.
• Model assumptions significantly impact the interpretation of experimental results.
• Previous studies have not fully addressed the comparative applicability of different models to specific experimental designs.

Purpose of the Study:

• To compare various mass transport models based on their assumptions and suitability for external perfusion experiments.
• To identify the most appropriate model for determining intestinal wall permeabilities in a specific experimental setup.
• To clarify how differing model assumptions affect permeability estimations.

Main Methods:

• Comparative analysis of mass transport models, focusing on assumptions regarding convection and diffusion.
• Application of residence time distribution analysis to evaluate model sensitivity.
• Evaluation of model performance using data from external perfusion experiments.
• Identification of the most appropriate model based on hydrodynamic considerations.

Main Results:

• All tested models reasonably fit the mass transfer data, despite differing assumptions about convection and diffusion.
• Significant variations in determined wall permeabilities were observed across different models.
• Residence time distribution analysis revealed higher sensitivity to model assumptions.
• Laminar flow in a cylindrical tube emerged as the most appropriate model for the specific experimental system.

Conclusions:

• The choice of mass transport model critically influences the calculated intestinal wall permeability.
• The laminar flow model implicitly addresses convection-diffusion issues, simplifying analysis.
• Accurate hydrodynamic definition is key to interpreting relative permeabilities.
• The proposed method yields a reliable estimate of wall permeability under perfect mixing conditions.