Effects of outflow pressure and vascular volume loading on thoracic duct lymph flow in adult sheep

1990 ◽  
Vol 258 (1) ◽  
pp. R240-R244 ◽  
Author(s):  
R. A. Brace ◽  
G. J. Valenzuela
Keyword(s):  
Flow Rate ◽  
Thoracic Duct ◽  
Venous Pressure ◽  
Ringer Solution ◽  
Lymph Flow ◽  
Thoracic Duct Lymph ◽  
Volume Loading ◽  
Vascular Volume ◽  
Duct Lymph ◽  
Lymph Duct

Studies have shown that lymph flow rate from several tissues depends on the pressure at the outflow end of the lymphatics. The left thoracic lymph duct is the largest lymphatic vessel and it transports a majority of the body's lymph. We varied outflow pressure for the left thoracic lymph duct independent of venous pressure in six unanesthetized, nonpregnant adult ewes with chronic lymphatic and venous catheters. When outflow pressure was negative, the thoracic duct lymph flow rate was independent of outflow pressure and averaged 0.040 +/- 0.004 (SE) ml.min-1.kg body wt-1. Lymph flow began to decrease with increasing outflow pressure only when outflow pressure was significantly greater than venous pressure. Above this breakpoint, lymph flow decreased linearly with outflow pressure and ceased at an outflow pressure of 25.6 +/- 4.2 mmHg. After vascular volume loading with lactated Ringer solution, steady-state thoracic duct lymph flow increased to 351 +/- 54% of control and was independent of outflow pressure when outflow pressure was negative. As outflow pressure was elevated, lymph flow began to decrease at the same breakpoint as before volume loading, and lymph flow ceased at the same outflow pressure as before volume loading. Thus this study shows that there is a plateau where thoracic duct lymph flow rate is independent of outflow pressure. In addition venous pressure under normal or volume-loaded conditions is not an impediment to thoracic duct lymph flow in unanesthetized sheep. Large increases in venous pressure are required to totally block thoracic duct lymph flow.

Thoracic duct lymph flow in pregnant sheep and response to blood volume expansion

1986 ◽  
Vol 250 (6) ◽  
pp. R1095-R1098 ◽  
Author(s):  
G. Valenzuela ◽  
L. L. Woods ◽  
R. A. Brace
Keyword(s):  
Blood Volume ◽  
Flow Rate ◽  
Thoracic Duct ◽  
Ringer Solution ◽  
Lymph Flow ◽  
Thoracic Duct Lymph ◽  
Volume Loading ◽  
Flow Rates ◽  
Pregnant Sheep ◽  
Duct Lymph

Left thoracic duct lymph flow rate averaged 0.077 +/- 0.003 (SD) and 0.078 +/- 0.003 ml X min-1 X kg-1 in near-term pregnant and nonpregnant sheep (P greater than 0.5). Lymph and plasma protein concentrations were unaltered in the pregnant compared with the nonpregnant animals. The thoracic duct lymph flow responses to three serial intravenous infusions of lactated Ringer solution were essentially the same in the pregnant and nonpregnant animals. Blood volume and vascular pressure changes during and after volume loading were essentially the same in both groups. In addition, terbutaline administration after volume loading caused no change in thoracic duct lymph flow rates. Thus the present study suggests that basal lymph flow rates, lymphatic function, and vascular as well as interstitial compliances are largely unaltered late in pregnancy in the sheep. In addition, beta-mimetic stimulation with terbutaline does not appear to suppress lymph flow rate.

Thoracic duct lymph flow and its measurement in chronically catheterized sheep fetus

1989 ◽  
Vol 256 (1) ◽  
pp. H16-H20 ◽  
Author(s):  
R. A. Brace
Keyword(s):  
Flow Rate ◽  
Thoracic Duct ◽  
Lymphatic Vessels ◽  
Lymph Flow ◽  
Thoracic Duct Lymph ◽  
Computer Technique ◽  
Venous Circulation ◽  
Duct Lymph ◽  
Unit Body Weight ◽  
Sheep Fetus

A method was developed for chronic catheterization of the left thoracic lymph duct at the base of the neck in the sheep fetus, which did not disrupt the other major lymphatic vessels that join the venous circulation at the same location. The lymphatic catheter was connected to a catheter in a jugular vein when lymph flow was not being recorded, so that the lymph continuously returned to the fetal circulation. Special consideration of catheter size to minimize flow resistance and treatment to prevent clotting were required. Individual animals were maintained up to 17 days with lymph flow continuing. In 13 fetuses averaging 128 days gestation (term = 147 days) at the time of catheterization, lymph flow rate was measured for 1 h each day for the first 7 postsurgical days with an on-line computer technique that continuously calculated lymph flow rate. Lymph flow averaged 0.64 +/- 0.17 (SD) ml/min in fetuses weighing 2.3-4 kg and tended to undergo a nonsignificant increase with time. Lymph and plasma protein concentrations did not change with time. In individual fetuses, large spontaneous variations in lymph flow rate occurred over periods of several seconds to a few minutes. Analysis showed that these variations in flow rate were not associated with fetal breathing movements. Thus the present study describes a technique for studying the dynamics of lymph flow in the unanesthetized sheep fetus in utero over a time period limited primarily by the length of gestation. In addition, it appears that thoracic duct lymph flow rate in the fetus per unit body weight averages three to four times that in the adult.

Intestinal lymphatic pressure increases during intravenous infusions in awake sheep

1993 ◽  
Vol 265 (3) ◽  
pp. R703-R705 ◽  
Author(s):  
R. E. Drake ◽  
Z. Anwar ◽  
S. Kee ◽  
J. C. Gabel
Keyword(s):  
Body Weight ◽  
Lymphatic System ◽  
Venous Pressure ◽  
Ringer Solution ◽  
Lymph Flow ◽  
The Body ◽  
Intravenous Fluid ◽  
Thoracic Duct Lymph ◽  
Duct Lymph ◽  
Intestinal Lymphatics

Intravenous fluid infusions cause increased venous pressure and increased lymph flow throughout the body. Together the increased lymph flow and increased venous pressure (the outflow pressure to the lymphatic system) should increase the pressure within the postnodal intestinal lymphatics. To test this, we measured the pressure in postnodal intestinal lymphatics and the neck vein pressure in five awake sheep. At baseline, the neck vein pressure was 1.2 +/- 1.5 (SD) cmH2O and the lymphatic pressure was 12.5 +/- 1.7 cmH2O. When we infused Ringer solution intravenously (10% body weight in approximately 50 min), the neck vein pressure increased to 17.3 +/- 0.9 cmH2O and the lymphatic pressure increased to 24.6 +/- 3.8 cmH2O (both P < 0.05). In two additional sheep, the thoracic duct lymph flow rate increased from 0.8 +/- 0.4 ml/min at baseline to 5.5 +/- 2.0 ml/min during the infusions. Our results show that postnodal intestinal lymphatic pressure may increase substantially during intravenous fluid infusions. This is important because increases in postnodal lymphatic pressure may slow lymph flow from the intestine.

Thoracic duct lymph flow responses to hemorrhage in the ovine fetus

1995 ◽  
Vol 269 (4) ◽  
pp. H1277-H1281
Author(s):  
R. A. Brace
Keyword(s):  
Flow Rate ◽  
Thoracic Duct ◽  
Plasma Proteins ◽  
Protein Concentration ◽  
Venous Pressure ◽  
Recovery Period ◽  
Lymph Flow ◽  
Late Gestation ◽  
Thoracic Duct Lymph ◽  
Plasma Protein Concentration

Blood volume returns toward normal after hemorrhage much more rapidly in the fetus than in the adult due to a rapid entry of fluid and plasma proteins into the fetal circulation. One potential source of fetal fluids and plasma proteins is the lymphatic system, since basal lymph flow rate and interstitial protein concentration are high in the fetus. Furthermore, studies in adults suggest that lymph flow rate may increase following hemorrhage. To test the hypothesis that hemorrhage induces an increase in lymph flow in the fetus, 15 late-gestation ovine fetuses underwent left thoracic duct catheterization with low-resistance catheters and were studied 5 or more days after surgery at 134 +/- 1 (SE) days gestation. The protocol included three successive 30-min periods: control, hemorrhage, and recovery. During the first 5 min of the hemorrhagic period, 61 +/- 4 ml of fetal blood were removed. The blood was reinfused over the first 5 min of the recovery period. After the hemorrhage, fetal arterial pressure, venous pressure, and heart rate decreased (analysis of variance, P < 0.001). These variables significantly increased above basal levels following blood reinfusion. Fetal hematocrit (P < 0.001) and plasma protein concentration (P < 0.05) also decreased after the hemorrhage and returned to control values after the reinfusion. Fetal lymph flow rate was 0.55 +/- 0.06 (SE) ml/min before the hemorrhage and decreased by a maximum of 30.3 +/- 6.3% (P < 0.001) at 8 min after the end of the hemorrhage. Lymph flow rate was reduced by an average of 19.1 +/- 6.6% during the hemorrhagic period and returned to prehemorrhage levels following blood reinfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II infusion increases thoracic duct lymph flow in chronically catheterized sheep

1987 ◽  
Vol 252 (5) ◽  
pp. R853-R858
Author(s):  
G. J. Valenzuela ◽  
C. W. Hewitt ◽  
A. D. Graham
Keyword(s):  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Flow Rate ◽  
Thoracic Duct ◽  
Pressor Response ◽  
Venous Pressure ◽  
Lymph Flow ◽  
Thoracic Duct Lymph ◽  
System Response ◽  
Base Line

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.

scholarly journals The Effect of Outflow Pressure upon Thoracic Duct Lymph Flow Rate in Fetal Sheep

1992 ◽  
Vol 32 (5) ◽  
pp. 585-588 ◽  
Author(s):  
Alfred L Gest ◽  
Derek K Bair ◽  
Mary C Vander Straten
Keyword(s):  
Flow Rate ◽  
Thoracic Duct ◽  
Lymph Flow ◽  
Thoracic Duct Lymph ◽  
Fetal Sheep ◽  
Duct Lymph

Effects of hypotonic, isotonic, and hypertonic fluids on thoracic duct lymph flow

1983 ◽  
Vol 245 (6) ◽  
pp. R785-R791
Author(s):  
R. A. Brace ◽  
G. G. Power
Keyword(s):  
Thoracic Duct ◽  
Protein Concentration ◽  
Plasma Osmolality ◽  
Ringer Solution ◽  
Lymph Flow ◽  
Whole Body ◽  
Thoracic Duct Lymph ◽  
Plasma Protein Concentration ◽  
Interstitial Fluid Volume ◽  
Duct Lymph

To test whether whole-body lymph flow responses to vascular volume loading depend on osmolality, we measured left thoracic duct lymph flow rate and protein concentration, plasma protein concentration, plasma osmolality, hematocrit, and arterial and venous pressures in pentobarbital-anesthetized, acutely nephrectomized dogs. Hypo- (100 mosmol), iso- (309 mosmol), and hypertonic (600 mosmol) saline, isotonic lactated Ringer solution, and 5% glucose in lactated Ringer solution (580 mosmol) were infused into the jugular vein (20 ml/kg per infusion over 5 min at 30-min intervals). Changes in blood, interstitial, and cellular volumes were calculated from the infused volume and from the hematocrit and plasma osmolality. The hypotonic fluid increased lymph flow about half as much as the isotonic fluid, whereas the hypertonic fluids increased lymph flow about twice as much as the isotonic infusions. Responses appeared independent of the osmotic agent, because hypertonic NaCl was as effective as hypertonic glucose in increasing lymph flow. Responses were not altered appreciably after lowering arterial pressure by 25 mmHg. The major finding of this study is that for every condition we explored, the excess lymph flow over 30 min (ELF in ml X kg-1 X 30 min-1) correlated with the change in interstitial fluid volume (delta ISFV in ml/kg); ELF = 0.076 delta ISFV (r = 0.909). These data suggest that cellular fluid that enters the interstitium is equally effective in increasing thoracic duct lymph flow as is vascular fluid that filters into the interstitium.

Blood volume response to drainage of left thoracic duct lymph in the ovine fetus

1994 ◽  
Vol 266 (3) ◽  
pp. R709-R713
Author(s):  
R. A. Brace
Keyword(s):  
Blood Volume ◽  
Flow Rate ◽  
Thoracic Duct ◽  
Lymph Flow ◽  
Thoracic Duct Lymph ◽  
Fetal Blood ◽  
Plasma Protein Concentration ◽  
Duct Lymph ◽  
Volume Response ◽  
Ovine Fetus

Although it is known that left thoracic duct lymph flow rate in the ovine fetus is several times that in the adult relative to body weight, the role of the lymphatic system in maintaining fetal blood volume has not been explored. In the present study, the left thoracic lymph duct was drained without return to the fetal circulation in 10 chronically catheterized animals for 7 h. Four experiments in which the lymph was returned to the circulation served as control. During the 7-h drainage, the total volume drained was 174.4 +/- 19.6 ml. Thoracic duct lymph flow rate decreased gradually and averaged 22.2 +/- 3.4% (SE) below control at 6-7 h compared with a small increase in the control experiments (analysis of variance: P = 0.0013 comparing 2 groups). Fetal blood volume decreased (P < 0.0001) by 8.2 +/- 1.1% at 3 h because of a decrease in plasma volume with a further small decrease in blood volume to 9.7 +/- 0.9% below normal at 7 h. The decreases in blood volume at 1, 3, 5, and 7 h were 49.5, 40.2, 24.6, and 21.7%, respectively, of the volume of lymph that was drained. Fetal vascular pressures and heart rate did not change significantly. Although protein concentrations in plasma (-6.8 +/- 1.3%) and lymph (-7.5 +/- 2.1%) decreased, the lymph-to-plasma protein concentration ratio remained constant at 0.72 +/- 0.01.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal thoracic duct lymph flow response to intravascular saline infusion

1988 ◽  
Vol 254 (6) ◽  
pp. R1007-R1010
Author(s):  
R. A. Brace
Keyword(s):  
Plasma Protein ◽  
Flow Rate ◽  
Thoracic Duct ◽  
Concentration Ratio ◽  
Protein Concentration ◽  
Isotonic Saline ◽  
Lymph Flow ◽  
Thoracic Duct Lymph ◽  
Plasma Protein Concentration ◽  
Duct Lymph

The left thoracic lymph duct was catheterized at the base of the neck in the sheep fetus at 123-136 days of gestation, and the lymphatic catheter was connected to a jugular vein catheter so that the lymph could return to the fetus. Lymph flow was studied 5 days after catheter implantation in the unanesthetized fetus. Basal fetal thoracic duct lymph flow rate per unit body weight averaged three times adult sheep values. After an infusion of 20 ml/kg of warmed isotonic saline into a fetal vein over 5 min, lymph flow rate increased significantly to 161 +/- 15% of control, with a peak at 8 min after termination of the infusion, and flow declined thereafter. The increased lymph volume above baseline values over 30 min averaged 5.7% of the infused volume and is similar to the adult response. Plasma and lymph protein concentrations decreased as did the lymph-to-plasma protein concentration ratio. The latter is opposite to what occurs in the adult under the same conditions. Thus the present study shows that even though the fetus has a much higher basal thoracic duct lymph flow rate than the adult, the responsiveness of the fetal lymphatic system to intravascularly infused saline is similar to that of the adult. The decrease in the lymph-to-plasma protein concentration ratio suggests that there may be differences between fetal and adult vascular-interstitial-lymphatic protein kinetics.

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