AJP - Heart and Circulatory Physiology, Vol 247, Issue 1 74-H79, Copyright © 1984 by American Physiological Society
Protein concentration of lymph and interstitial fluid in the rat tail
K. Aukland, G. C. Kramer and E. M. Renkin
Lymph was collected from tail lymphatics of anesthetized rats, subcutaneous
interstitial fluid was obtained by implanting nylon wicks, and tendon
interstitial fluid was obtained by centrifugation of pieces of tendon.
Spontaneous lymph flow rates averaged 70 nl X min-1 X g skin-1. Protein
concentrations and colloid osmotic pressures of sampled fluids differed
significantly. Tail lymph had the highest protein concentration relative to
plasma [lymph-to-plasma ratio 0.71 +/- 0.03 (SE) n = 10], followed by wick
fluid (0.62 +/- 0.02, n = 9), with tendon fluid lowest (0.50 +/- 0.03, n =
10). Albumin and immunoglobulin G (IgG) concentrations in samples of tail
skin and tendon were assayed by rocket immunoelectrophoresis. Comparison of
their distribution volumes at lymph or tendon fluid concentrations,
respectively, with interstitial fluid volumes measured as 2-h
51Cr-ethylenediaminetetraacetic acid space minus 5-min 125I-albumin space
indicated that 50-60% of the interstitial volume in these tissues is not
available for distribution of albumin or IgG. Low lymph flow and high
interstitial protein content of rat tail indicate a slow turnover of
interstitial protein. This suggests that interstitial washout of protein
plays a role in limiting edema only after a sustained or chronic increase
in fluid filtration.
