Journal of Applied Physiology, Vol 58, Issue 2 514-520, Copyright © 1985 by American Physiological Society
Surfactants identified in lung lymph and their ability to act as abhesives
B. A. Hills, B. D. Butler and R. E. Drake
Phospholipid has been extracted from pulmonary lymph collected from 10
dogs. Thin-layer chromatography was used to identify phosphatidylcholine
(PC) 55.6 +/- 2.9%, sphingomyelin 21.3 +/- 1.7%, phosphatidylethanolamine
11.2 +/- 4.9%, and lysophosphatidylcholine 5.9 +/- 0.8%. All extracts
proved highly surface active, reducing the surface tension of saline to
27.7 +/- 0.7 dyn/cm upon 80% film compression and increasing the maximum
contact angle on glass (theta) from 7 +/- 1 to 47.4 +/- 1.4 degrees. The
hydrophobic properties induced on glass were further demonstrated by the
ability to cause saline to withdraw and expose a dry surface. A standard
adhesion test was used to measure the "tack" produced by the major proteins
in lymph. However, when the surface energy of the hydrophilic glass
surfaces was reduced by a monolayer of lymph phospholipid extract or an
equivalent mixture of synthetic surfactants, the adhesive force was reduced
by 79 +/- 4% for albumin and 55 +/- 4% for globulin. As a 0.1% liposomal
suspension, PC gave 55% release with albumin. Reversible bonding of the
lumen of lymph vessels by the "tacky" proteins present is discussed as a
possible factor contributing to the large changes in flow resistance known
to occur in the pulmonary lymphatic system.
