AJP - Regulatory, Integrative and Comparative Physiology, Vol 240, Issue 5 282-R288, Copyright © 1981 by American Physiological Society
Thoracic duct lymph flow and protein flux dynamics: responses to intravascular saline
R. A. Brace and G. G. Power
Fluid and protein flux responses in the left thoracic duct and vasculature
were measured in pentobarbital-anesthetized, nephrectomized, adult dogs
before and after four successive intravascular saline infusions of 2% of
body weight each. We found three main characteristics of the thoracic lymph
flow and protein flux responses to the intravenous saline: 1) lymph flow
reached a peak and then decreased by approximately 40% after each infusion;
2) the maximum lymph flow occurred 5-7 min after terminating each infusion;
and 3) the lymph-to-plasma protein concentration ratio fell more than may
be expected from the distribution of the infused saline. We were unable to
explain these experimental data with a simple two-compartment mathematical
model representing the vascular and interstitial spaces. To adequately
explain the data, the model had to be expanded to four compartments
representing a vascular compartment, two interstitial compartments each
with different capillary protein permeabilities, and a lymphatic
compartment. We also found it necessary to include interstitial stress
relaxation, a nonlinear function curve for lymph flow versus interstitial
fluid pressure, and a complaint lymphatic system.
