AJP - Regulatory, Integrative and Comparative Physiology, Vol 262, Issue 5 892-R894, Copyright © 1992 by American Physiological Society
Effect of increased neck vein pressure on intestinal lymphatic pressure in awake sheep
R. E. Drake and R. D. Abbott
Center for Microvascular and Lymphatic Studies, University of Texas Medical School, Houston 77030.
Lymphatic vessels from the intestines drain into the thoracic duct, and the
thoracic duct empties into veins in the neck. Thus increases in neck vein
pressure (PNV) might slow intestinal lymph flow, provided the increased
pressure is reflected upstream through the lymphatic vessels. To test the
effect of increases in PNV on lymphatic pressure, we cannulated intestinal
lymphatics in the direction of flow in six sheep. After the sheep recovered
from surgery, we measured the pressure in the lymphatics (Px) as we
increased PNV in steps. Px increased only slightly (but significantly) from
7.4 +/- 2.0 to 11.4 +/- 5.2 (SD) cmH2O when we increased PNV from baseline
(0.8 +/- 2.4 cmH2O) to 37.4 +/- 4.1 cmH2O. However, when we simulated an
increased lymph flow by infusing Ringer solution into the lymphatics at
1,000 microliters/min, Px increased to 24.6 +/- 7.0 cmH2O at PNV equal to
37.1 +/- 5.3 cmH2O. These results indicate that, at normal lymph flow
rates, increases in neck vein pressure cause only small increases in
intestinal lymphatic pressure. On the other hand, when lymph flow is
elevated, increases in neck vein pressure may substantially increase
lymphatic pressure and thus slow intestinal lymph flow.
