Premium
Co‐requirement of NADPH oxidase (NADPHox)‐derived Reactive Oxygen Species (ROS) and Nitric Oxide (NO) for Platelet Activating Factor (PAF)‐induced microvascular hyperpermeability
Author(s) -
González Francisco G,
DíazParra Cristian,
León Luisa,
Uslar Wilhelm F,
Velarde Victoria,
Boric Mauricio P
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a489-c
Subject(s) - chemistry , platelet activating factor , nitric oxide , vascular permeability , reactive oxygen species , pharmacology , snap , enos , cheek pouch , nitric oxide synthase , biochemistry , biophysics , immunology , microbiology and biotechnology , endocrinology , biology , organic chemistry , computer graphics (images) , hamster , computer science
The increase in permeability to macromolecules induced by PAF requires an active endothelial nitric oxide synthase (eNOS); however, NO donors do not cause hyperpermeability, suggesting that NO acts as a co‐signal in PAF transduction. Thus, we assessed the participation of ROS, particularly O 2 − , which combined with NO can produce ONOO − . Macromolecular transport was measured in the cheek pouch of anesthetized male hamsters (110–130g, Nembutal 50 mg/kg), under intravital microscopy, by clearance of 150‐KDa FITC‐Dextran (C‐Dx). PAF applied topically (10 −7 M, 5 min) increased C‐Dx ~8‐fold above basal, peaking at 30 min. The magnitude and duration of PAF response was increased by TEMPOL (a ROS scavenger, SOD‐mimetic, 10 −5 M), effect not mediated by H 2 O 2 production since it was not affected by catalase (500 U/ml). On the other hand, NADPHox inhibitor, Apocynine 10 −5 M reduced PAF‐induced hyperpermeability. Co‐application of Apocynine and TEMPOL cancelled each other effects on PAF‐induced permeability, indicating independent mechanisms. The effect of PAF on C‐Dx, was abolished by NOS inhibition (L‐NNA, 10 5 M), but restored by co‐superfusion with NO donor, SNAP (10 −6 M). Surprisingly, in this “NO clamp” condition (L‐NNA+ SNAP), TEMPOL inhibited PAF‐induced hyperpermeability. These results reveal a necessary, though permissive role for NO, and suggest that in addition to NO release, PAF requires NADPHox‐induced O 2 − generation, and possible ONOO − formation to cause hyperpermeability. Supported by Grant Fondecyt 1040816