Journal of Applied Physiology, Vol 45, Issue 2 182-189, Copyright © 1978 by American Physiological Society
Tracheobronchial secretions collected from intact dogs. I. Protein and mucous glycoprotein composition
M. J. Reasor, G. K. Adams 3rd, D. F. Proctor and R. J. Rubin
Tracheobronchial secretions (TBS) were collected in situ from intact,
anesthetized dogs, and the protein composition and distribution were
studied. TBS were separated into supernatant and pellet phases by
centrifugation. The supernatant phase comprised 85%, by weight, of the
secretory mixture; yet it contained only 58% of the total protein. Peptides
of apparent molecular weights ranging from 16,000 to 154,000 daltons were
present in the supernatant phase. Electrophoretic and immunochemical
comparisons with canine serum suggested that certain of the peptides were
of plasma origin including albumin, IgG, IgA, and IgM. Albumin and IgG
comprised approximately 70% of the supernatant phase protein. Three percent
of the total TBS protein was contributed by the peptide portion of mucous
glycoproteins (mucins), and 97% of the mucin protein separated into the
pellet phase. When compared to mucus collected from a canine tracheal
pouch, TBS was less concentrated in mucins, and differences were observed
in electrophoretic profiles between the two samples.
