Nitric oxide attenuates H2O2-induced endothelial barrier dysfunction: mechanisms
of protection.
Gupta, Mahesh P., Michael D. Ober, Carolyn Patterson, Mohammed Al-Hassani,
Viswanathan Natarajan, and C. Michael Hart.
1Department of Medicine, Indiana University and Richard L. Roudebush Veterans
Affairs Medical Centers, Indianapolis, Indiana 46202; and 2Department of Medicine,
Johns Hopkins University, Baltimore, Maryland 21224
APStracts 7:0241L, 2000.
Nitric oxide («lrad»NO) attenuates hydrogen peroxide (H2O2)-mediated injury in
porcine pulmonary artery endothelial cells (PAECs) and modulates intracellular levels of
cGMP and cAMP. We hypothesized that «lrad»NO attenuates H2O2-induced PAEC
monolayer barrier dysfunction through cyclic nucleotide-dependent signaling
mechanisms. To examine this hypothesis, cultured PAEC monolayers were treated with
H2O2, and barrier function was measured as transmonolayer albumin clearance. H2O2
caused significant PAEC barrier dysfunction that was attenuated by intracellular as well
as extracellular «lrad»NO generation. «lrad»NO increased PAEC cGMP and cAMP
levels, but treatment with inhibitors of soluble guanylate cyclase or protein kinase G did
not abrogate «lrad»NO-mediated barrier protection. In contrast, H2O2 decreased protein
kinase A activity, and inhibiting protein kinase A abrogated the protective effect of
«lrad»NO. H2O2-induced barrier dysfunction was not associated with decreased levels of
cGMP or cAMP. 3-Isobutyl-1-methylxanthine and the cGMP analog 8-bromo-cGMP had
little effect on H2O2-mediated endothelial barrier dysfunction, whereas 8-bromo-cAMP
plus 3-isobutyl-1-methylxanthine was protective. These results indicate that «lrad»NO
modulates vascular endothelial barrier function through cAMP-dependent signaling
mechanisms.
Received 28 October 1999; accepted in final form 9 August 2000
APS Manuscript Number L353-9.
Article publication pending Am J Physiol Lung Cell Mol Physiol
ISSN 1080-4757 Copyright 2000 The American Physiological Society.
Published in APStracts on 7 November 2000