Poroelastic theory of transcapillary flow: effects of endothelial glycocalyx deterioration

The luminal surface of endothelial cells is lined with a carbohydrate-rich layer known as the endothelial glycocalyx. Identification of the structural properties of the glycocalyx has led investigators to examine its various functions and it has since been recognized as playing a role in many physiological processes, one of which is the regulation of fluid and protein exchange across the capillary wall. Experimental observations in which the glycocalyx was degraded in rat myocardial capillaries showed fluid accumulation in the tissue, suggesting that the glycocalyx acts as a protective barrier against edema. In this work we seek to quantify the observed edema formation by using our earlier poroelastic model to examine the consequences of glycocalyx deterioration on transcapillary filtration. Upon enzymatic treatment the properties of the glycocalyx, such as its thickness and permeability, will be modified, and our purpose here is to investigate quantitatively how changes in these parameters affect the magnitude of the fluid filtration through the capillary wall. We compare our results with both experimental data as well as other theoretical models where applicable, discussing the implications of the models as well as the limitations of comparison. This work provides the basis for further experiments that may better characterise many of the parameters involved in this process.