Four region blood-tissue exchange (BTEX) model used to fit data from Schwartz 1999 MID experiments involving cardiac endothelial transport and metabolism of adenosine and inosine.

Description

 This blood-tissue exchange (BTEX) model represents a "tissue cylinder" consisting of four 
 regions. The four regions are capillary plasma, p; endothelial cell, ec; interstitial 
 fluid, isf; and parenchymal cell, pc; and are separated by three barriers--the luminal 
 or plasma surface and endothelial cell layer; the albuminal surface of the endothelial 
 cell facing the interstitium; andthe membrane between the interstitial fluid and 
 parenchymal cell. In addition, there is a diffusional path from plasma to ISF bypassing 
 endothelial cells via intercellular clefts. The model is used to fit data from Adenosine and 
 Inosine uptake and metabolism experiments in animal hearts done by Schwartz et al. 1999.
 Metabolism within a region is modeled as constant or first-order consumption term.

Figure: Adenosine (Ado -green) transport and metabolism in rabbit heart as a function of time after injection. Red is AraH, an extravascular reference, and brown is Inosine (Ino) a metabolite of Ado. Dashed lines are model fit to data (Schwartz 1999). Concentration is log scale.

Equations

The equations for this model may be viewed by running the JSim model applet and clicking on the Source tab at the bottom left of JSim's Run Time graphical user interface. The equations are written in JSim's Mathematical Modeling Language (MML). See the Introduction to MML and the MML Reference Manual. Additional documentation for MML can be found by using the search option at the Physiome home page.