AJP - Regulatory, Integrative and Comparative Physiology, Vol 239, Issue 5 401-R406, Copyright © 1980 by American Physiological Society
Disposition of 5-hydroxytryptamine in lungs of developing rats
K. B. Wallace, M. D. Bailie, J. B. Hook and R. A. Roth
The pulmonary vasculature has been implicated in the clearance of several
vasoactive peptides, prostaglandins, and biogenic amines from the
circulation. In view of the age-related differences in the metabolism of
angiotensin by intact lungs, it was of interest to examine the maturation
of 5-hydroxytryptamine (5-HT) disposition by isolated perfused lungs. Lungs
from newborn and adult rats were perfused with Krebs bicarbonate buffer
containing 0.1 microM 5-[14C]HT and samples of the effluent medium
collected and analyzed for 5-HT and metabolite. Adult lungs removed and a
greater fraction of perfused 5-HT than did lungs from 7-day-old rats. No
age-related difference in monoamine oxidase (MAO) activity was observed;
however, lung slices from adult rats incubated with 5-[14C]HT accumulated
radiolabel at a greater rate than did slices from lungs of 7-day-old rats.
The age-related difference in 5-HT clearance by intact lungs may be
attributable to a relative deficiency in the facilitated transport process
for 5-HT in newborns and may reflect a general functional maturation of
processes associated with pulmonary endothelial cell membranes.
