AJP - Regulatory, Integrative and Comparative Physiology, Vol 259, Issue 4 780-R785, Copyright © 1990 by American Physiological Society
Effect of outflow pressure on liver lymph flow in unanesthetized sheep
R. E. Drake and J. C. Gabel
Center for Microvascular and Lymphatic Studies, University of Texas Medical School, Houston 77030.
We used lymph flow rate (QL) to lymphatic vessel outflow pressure (Po)
relationships to analyze lymphatic flow in five unanesthetized sheep with
liver lymphatic cannulas. The olecranon was the zero reference level for
pressures. Increases in Po did not change QL until Po exceeded 19 +/- 4
(SD) cmH2O. However, for Po greater than 19 +/- 4 cmH2O, QL decreased
linearly with increases in Po. We fit regression lines to the QL vs. Po
data for Po greater than 19 cmH2O and estimated the effective lymphatic
resistance (RL) as -delta Po/delta QL. The effective pressure driving lymph
(PL) was the Po at which QL = 0. At baseline, RL = 0.18 +/- 0.10
cmH2O.min.microliter-1 and PL = 29.6 +/- 3.4 cmH2O. When we increased
hepatic vein pressure by 5.7 +/- 1.7 cmH2O, QL increased to 6.2 +/- 3.2
times baseline, RL decreased to 0.050 +/- 0.015 cmH2O.min.microliter-1, and
PL increased to 37.1 +/- 3.5 cmH2O (P less than 0.05). Thus 1) liver lymph
flow is very sensitive to increases in hepatic vein pressure, 2) there is a
substantial QL vs. Po plateau for liver lymphatics, and 3) after hepatic
venous pressure elevations, liver lymph flow increases as if it were driven
by a higher pressure through a lower resistance.
