Autonomic involvement in the lymphatic delivery of fibrinogen

Fibrinogen concentrations in thoracic duct lymph and plasma were measured in 64 dogs before and following the intravenous administration of one of the following agents: saline, ephedrine, methacholine, or neostigmine. Measurements of hematocrit, lymphatic flow, arterial pressure, heart rate, and respiratory rate were recorded also. Half of the dogs in each of the above groups were premedicated with atropine, the other half with saline. The rate of lymphatic flow increased only in dogs premedicated with saline and receiving ephedrine, methacholine, or neostigmine. Blood and lymph fibrinogen concentrations increased only in dogs receiving ephedrine; this increase was not observed in any dog premedicated with atropine. Fibrinogen delivery (milligrams fibrinogen delivered via the thoracic duct per minute), therefore, was dependent on parasympathetic activity and primarily was a reflection of the induced increase in rate of lymphatic flow. The increased flow was related to changes in hematocrit and to a lesser extent to changes in respiratory rate. Evidence and inductive reasoning are presented to support the concept of extravascular storage of fibrinogen and to propose a possible mechanism by which depletion and repletion of these stores is accomplished.

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Effects of sustained lymph drainage on cardiovascular function and thoracic duct lymph in sheep

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1989.256.4.r867 ◽

1989 ◽

Vol 256 (4) ◽

pp. R867-R874

Author(s):

G. J. Valenzuela ◽

C. W. Hewitt ◽

G. C. Kramer ◽

Y. Do ◽

W. A. Hseuh

Keyword(s):

Arterial Pressure ◽

Plasma Protein ◽

Thoracic Duct ◽

Protein Concentration ◽

Lymph Flow ◽

Escape Rate ◽

Thoracic Duct Lymph ◽

Lymph Drainage ◽

Plasma Protein Concentration ◽

Duct Lymph

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)

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