Journal of Applied Physiology, Vol 71, Issue 1 99-103, Copyright © 1991 by American Physiological Society
Active lymphatic pumping and sheep lung lymph flow
R. E. Drake, D. Weiss and J. C. Gabel
Center for Microvascular and Lymphatic Studies, University of Texas Medical School, Houston 77030.
Active (intrinsic) lymphatic pumping may be an important factor determining
lymph flow from the lungs. Unfortunately, in most experiments, it is very
difficult to determine the influence of active pumping vs. passive factors
on lymph flow. However, 1) the pumping activity (stroke volume and
frequency) of isolated lymphatic segments varies nonlinearly with
transmural pressure, and 2) the lung lymph flow from awake sheep varies
nonlinearly with lymphatic outflow pressure. Accordingly, if lymphatic
pumping significantly influences lung lymph flow, then it should be
possible to describe the sheep lung lymph flow vs. outflow pressure data
with the pumping activity data. To test this, we used published lymphatic
pumping activity data to develop a mathematical model of the lymphatic pump
for a segment of lymphatic vessel. Flow vs. outflow pressure relationships
obtained from simulations with this model were very similar to the data
from sheep. Our results indicate that both passive factors and active
lymphatic pumping contribute to lymph flow, and our model may allow
investigators to distinguish the effects of active pumping vs. passive
factors in the regulation of lymph flow.
