AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 4 867-R874, Copyright © 1989 by American Physiological Society
Effects of sustained lymph drainage on cardiovascular function and thoracic duct lymph in sheep
G. J. Valenzuela, C. W. Hewitt, G. C. Kramer, Y. Do and W. A. Hseuh
Department of Obstetrics and Gynecology, Loma Linda University 92354.
We studied the effect of lowering the plasma protein concentration on the
cardiovascular function and thoracic duct lymph in awake adult sheep.
Hypoproteinemia was induced in seven nonpregnant, splenectomized sheep by
drainage of the thoracic duct lymph over a 5-day period. The plasma protein
went from a mean of 6.4 +/- 0.2 (SE) to 4.9 +/- 0.2 g/dl on day 5, and the
lymph-to-plasma protein concentration ratio decreased from 0.74 +/- 0.01 on
day 1 to 0.48 +/- 0.04 on day 5. The percentage composition of the protein
fractions in plasma and lymph remained unchanged. Lymph flow was 1.79 +/-
0.37 and 1.28 +/- 0.10 ml/min for days 1 and 5, respectively. Renin
concentration in plasma increased 50-fold by day 5. Arterial pressure fell
from 102.9 +/- 5.4 to 72.7 +/- 4.4 mmHg by day 5. Mean hematocrit was 28.9
+/- 1.7 at day 1, which was not significantly different than 24.6 +/- 2.9
at day 5 and indicated that the plasma volume did not decrease. Body weight
also did not change significantly. There was a decrease in the
transcapillary protein escape rate, determined as the thoracic lymph flow
rate multiplied the lymph protein concentration, that suggests adaptations
in the microcirculation to decrease vascular-to-interstitial protein
transfer during hypoproteinemia. Hypoproteinemic animals also demonstrated
greater vascular retention of a fluid volume challenge. In conclusion, the
sheep adaptations to sustained hypoproteinemia produced by lymph drainage
were a significant decrease in arterial pressure, large increases in
vascular compliance and renin concentration, and reduced transcapillary
escape rate of protein.(ABSTRACT TRUNCATED AT 250 WORDS)
