Journal of Applied Physiology, Vol 45, Issue 2 190-194, Copyright © 1978 by American Physiological Society
Tracheobronchial secretions collected from intact dogs. II. Effects of cholinomimetic stimulation
M. J. Reasor, D. Cohen, D. F. Proctor and R. J. Rubin
The effect of cholinomimetic stimulation on the quantity and composition of
tracheobronchial secretions (TBS) collected from intact dogs was studied.
After the administration of methacholine chloride, the collection rate of
TBS increased over threefold within 10 min and returned to the control
level by 50 min. Even though there was an increase in the total amount of
protein collected, the protein concentration of the secretions decreased
initially by 40%, returning to normal by 30 min. This was the result of an
apparent dilution of the secretions by nonproteinaceous components. In
addition, at 10 min, there was an increase in the protein associated with
mucins. These responses were blocked by the preadministration of atropine.
When TBS was separated into supernatant and pellet phases by
centrifugation, we found that, following methacholine, there was a 35%
increase in the ratio of albumin to IgG in the supernatant phase. These
results suggest that the increased secretion due to methacholine may
result, in part, by a selective filtration of fluid from the interstitial
and/or vascular compartment(s) with proteins appearing in the secretory
mixture based partially on their size.
