Transport in lymphatic capillaries: ii. microscopic velocity
measurement with fluorescence recovery after photobleaching.
Berk, David A., Melody A. Swartz, Anders J. Leu, and Rakesh K. Jain.
Edwin L. Steele Laboratory, Department of Radiation Oncology,
Massachusetts General Hospital and Harvard Medical School, Boston, MA
02114, Department of Chemical Engineering, Massachusetts Institute of
Technology, Cambridge, MA 02139
APStracts 2:0309H, 1995.
Despite its relevance to the physiology of lymph formation and
propulsion, the instantaneous flow velocity in single lymphatic
capillaries has not been measured to date. The method of Fluorescence
Recovery After Photobleaching (FRAP) was adapted for this purpose and
used to characterize flow in the lymphatic capillaries in tail skin
of anesthetized mice during a constant-pressure intradermal injection
of FITC-Dextran (molecular weight 2 million). The median lymph flow
velocity was 4.7 m/s, and the velocity magnitude ranged from zero to
29 m/s. The direction of flow was generally proximal, but stasis and
backflow toward the site of injection was also detected. Evidence for
oscillatory flow was detected in some FRAP experiments, and in
separate experiments a periodicity of approximately 120 min-1,
directly correlated to respiration frequency, was measured by
tracking the motion of fluorescent latex microspheres (diameter 1 m)
introduced into the lymphatic capillary network. The velocity
magnitude showed a correlation with duration of infusion, but not
with distance from injection site. It is speculated that the temporal
decay of mean velocity magnitude could be related to the relaxation
of local pressure gradients as partially collapsed vessels expand
during the infusion.
Received 9 March 1995; accepted in final form 10 July 1995.
APS Manuscript Number H226-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.