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Interconnected-tubes model of hepatic elimination: steady-state considerations
Y G Anissimov1, A J Bracken, M S Roberts
1Department of Medicine, The University of Queensland, Princess Alexandra Hospital, Wooloongabba, Qld, 4102, Australia.
Journal of Theoretical Biology
|August 12, 1999
Summary
The interconnected-tubes model explains hepatic transport by solute exchange between sinusoids. It introduces a heterogeneity number (H(N)) to quantify variations in enzyme distribution and flow rates, improving upon the dispersion number (D(N)).
Area of Science:
- Pharmacokinetics and Drug Metabolism
- Physiology
- Computational Biology
Background:
- Hepatic transport and elimination involve complex sinusoidal interactions.
- Previous models like the dispersion model simplify these interactions.
- Understanding solute movement in the liver is crucial for drug efficacy and safety.
Purpose of the Study:
- To apply the interconnected-tubes model to steady-state hepatic extraction.
- To express the dispersion number in terms of physiological determinants.
- To introduce and analyze a new heterogeneity number (H(N)) for hepatic transport.
Main Methods:
- Modeling solute interchange between parallel tubes representing sinusoids.
- Developing a zeroth-order approximation for the dispersion model.
- Deriving equations for output concentrations using the heterogeneity number (H(N)).
Main Results:
- The dispersion number (D(N)) is defined by flow heterogeneity and interconnection density.
- Output concentrations are predicted using H(N), incorporating enzyme and flow variations.
- H(N) can be less than, greater than, or equal to D(N) based on correlations in sinusoidal parameters.
Conclusions:
- The interconnected-tubes model provides a more comprehensive understanding of hepatic transport.
- H(N) offers a refined metric for hepatic sinusoidal heterogeneity.
- This model enhances predictions of solute elimination and drug disposition in the liver.