Confocal and electron microscopic localization of fitc-albumin in
h2o2-induced pulmonary edema.
Pietra, Giuseppe G., and Lewis W. Johns.
Division of Anatomic Pathology, Department of Pathology and
Laboratory Medicine, University of Pennsylvania Medical School,
Philadelphia, PA 19104
APStracts 2:0402A, 1995.
Fluorescein-conjugated bovine serum albumin (FITC-BSA ) was used to
detect sites of protein leakage in rat lungs perfused for 15-60 min
with H2O2 (75,150 and 300 M ) . Leaky vessels were localized by
confocal laser microscopy. Endothelial routes of protein leakage were
identified by electron microscopy after photoconversion of FITC-BSA
to an osmiophilic diaminobenzidine product. Transport of FITC-BSA
into the alveolar interstitium was assessed by immunogold labeling
and anti-FITC-antibodies. We detected leakage of FITC-BSA through
transendothelial gaps in the pulmonary arterial endothelium after 30
min perfusion with 300 M H2O2 and after 60 min perfusion with 150 M
H2O2. Junctional permeability and distribution of ZO-1 protein in the
arterial endothelium were unchanged. Microvascular permeability to
FITC-BSA was not increased in lungs perfused with H2O2. In lungs
perfused with 300 M H2O2 progressive extravasation of albumin was
associated with significant increases in water content and perfusing
pressure. We conclude that the pulmonary arterial endothelium is the
primary target of circulating H2O2.
Received 9 November 1994; accepted in final form 14 August 1995.
APS Manuscript Number A1151-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.