Journal of Applied Physiology, Vol 59, Issue 3 691-697, Copyright © 1985 by American Physiological Society
Alveolar transfer of prostaglandin E2 in isolated perfused guinea pig lungs
B. R. Pitt, R. Moalli, S. F. Man and C. N. Gillis
Alveolar transfer of prostaglandin E2 (PGE2) was characterized in isolated
perfused guinea pig lungs (n = 19) by measuring radioactivity appearing in
the venous effluent during 30 min after intratracheal instillation of
[3H]PGE2, [14C]-mannitol, and [125I]iodoantipyrine. Recovery of
lipid-soluble [125I]iodoantipyrine [91 +/- 3% (SE)] after 30 min was used
to estimate total 3H and 14C delivered to the exchanging region of lung at
time 0. In seven control lungs, 58 +/- 4% of [14C]mannitol and 16 +/- 4% of
[3H]PGE2 was retained 10 min after instillation. Neither perfusion with
diphloretin phosphate (10 micrograms/ml; n = 4) nor hypothermia (5 degrees
C; n = 5) significantly affected the amount of [14C]mannitol retained;
however, [3H]PGE2 remaining in these lungs increased significantly to 36
+/- 4 and 53 +/- 2%, respectively. Addition of unlabeled PGE2 (200
micrograms) to the instilled solution (n = 3) increased retention of both
[14C]mannitol (80 +/- 3%) and [3H]PGE2 (65 +/- 4%). Alveolar transfer of
[3H]PGE2 was calculated as the difference in percent retention of
[14C]mannitol and [3H]PGE2 and normalized to that of [14C]mannitol. After
10 min, alveolar transfer of [3H]PGE2 was 71 +/- 8% in control lungs but
was decreased to 26 +/- 7, 10 +/- 5, and 19 +/- 6% by diphloretin
phosphate, hypothermia, or unlabeled PGE2, respectively. These data suggest
that alveolar clearance of PGE2 involves a saturable drug- and
temperature-sensitive process.
