AJP - Heart and Circulatory Physiology, Vol 253, Issue 6 1548-H1556, Copyright © 1987 by American Physiological Society
Fluid exchange in skeletal muscle with viscoelastic blood vessels
J. Lee, E. P. Salathe and G. W. Schmid-Schonbein
Department of Applied Mechanics and Engineering Sciences, Bioengineering, University of California, San Diego, La Jolla 92093.
A mathematical model of capillary-tissue fluid exchange in a viscoelastic
blood vessel is presented, and the Landis occlusion experiment is
simulated. The model assumes that the fluid exchange is governed by
Starling's law and that the protein and red blood cells are conserved in
the capillary. Before occlusion, in the steady flow state, the pressure in
the capillary decreases from the arterial to venous end due to viscous
dissipation. After occlusion a constant pressure is established along the
capillary. We assume the capillary to be distensible with viscoelastic wall
properties. Immediately following occlusion an instantaneous distension of
the capillary occurs. The vessel continues to expand viscoelastically while
fluid is filtered for a period of several minutes, until it reaches an
equilibrium state. A full numerical solution of the governing equations has
been obtained. We use this model to compute the distance variation between
two labeled erythrocytes as obtained in the Landis occlusion experiment and
compare the results with experimental data obtained recently for the
spinotrapezius muscle in our laboratory. The new model can fit the
experimental data better than previous models that neglect the
distensibility of the capillaries.
