AJP - Regulatory, Integrative and Comparative Physiology, Vol 252, Issue 5 853-R858, Copyright © 1987 by American Physiological Society
Angiotensin II infusion increases thoracic duct lymph flow in chronically catheterized sheep
G. J. Valenzuela, C. W. Hewitt and A. D. Graham
Both pregnancy and estrogen administration are associated with a decrease
in the systemic vasculature pressor response to angiotensin II infusion;
however, the lymphatic vessel system response is not clear. In the present
study we infused angiotensin II to nine nonpregnant splenectomized ewes
with 0.1, 10, or 1,000 ng X kg-1 X min-1 for a 5-min period at each dose.
At the lowest dose the mean arterial pressure increased from 10 to 20% over
base line. At the highest dose, the left thoracic duct flow rate peaked at
361% 10 min after the infusion was started, whereas arterial pressure
peaked at 183% of the control value. Peak lymph flow occurred 4-6 min after
the maximal increase in mean systemic arterial pressure. Neither hematocrit
nor venous pressure were altered at any of the doses administered. This
suggests that the interstitial fluid space pressure remained unchanged and
that the increase in lymph flow was not secondary to fluid transfer from
the intravascular system. We postulate, therefore, that the effect of
angiotensin II in the increase of lymph flow rate is by direct action on
the lymphatic vessels themselves.
