AJP - Heart and Circulatory Physiology, Vol 258, Issue 1 24-H28, Copyright © 1990 by American Physiological Society
Caudal mediastinal node lymph flow in sheep after histamine or endotoxin infusions
N. Matsumoto, K. Koike, S. Yamada and N. C. Staub
Cardiovascular Research Institute, University of California, San Francisco 94143-0130.
To determine whether intrathoracic nonpulmonary structures (caudal
mediastinal node or esophagus) are reputed to affect lung lymph dynamics,
we studied anesthetized, open-thorax, prone, ventilated sheep in which all
lung afferent lymphatics to the caudal mediastinal node were eliminated.
When we increased left atrial pressure by 20 cmH2O in four sheep, there was
no effect on caudal mediastinal node efferent lymph flow or protein
concentration, thus providing the completeness of the surgical preparation.
In four sheep, intravenous histamine infusions (3 micrograms
base.kg-1.min-1) had no effect on caudal mediastinal node lymph flow or
protein concentration. In seven sheep with intact lung lymphatics,
Escherichia coli endotoxin infusion (1 microgram/kg over 20 min) increased
lymph flow with high lymph protein concentration during the late phase (2-6
h). In seven sheep, after all lung lymphatic afferents had been cut,
endotoxin did not affect caudal mediastinal node lymph flow, although lymph
protein concentration was decreased in the early 0-2 h, "hypertensive")
phase. We conclude that at the concentrations tested, which are those
regularly used in sheep lung experiments, the effects of histamine and
endotoxin on caudal mediastinal node lymph flow and protein concentration
are limited to the lung.
