Citation

Honavar J, Bradley E, Bradley K, Oh JY, Vallejo MO, Kelley EE, Cantu-Medellin N, Doran S, Dell'italia LJ, Matalon S, Patel RP. Toxicology 2014; 321: 96-102.

Affiliation

Department of Pathology, University of Alabama at Birmingham, Birmingham AL 35294; Centers for Free Radical Biology and Lung Injury and Repair, University of Alabama at Birmingham, Birmingham AL 35294. Electronic address: rakeshp@uab.edu.

Copyright

(Copyright © 2014, Elsevier Publishing)

DOI

10.1016/j.tox.2014.04.005

PMID

24769334

Abstract

Exposure to chlorine (Cl2) gas during industrial accidents or chemical warfare leads to significant airway and distal lung epithelial injury that continues post exposure. While lung epithelial injury is prevalent, relatively little is known about whether Cl2 gas also promotes injury to the pulmonary vasculature. To determine this, rats were subjected to a sub-lethal Cl2 gas exposure (400ppm, 30min) and then brought back to room air. Pulmonary arteries (PA) were isolated from rats at various times post-exposure and contractile (phenylephrine) and nitric oxide (NO)-dependent vasodilation (acetylcholine and mahmanonoate) responses measured ex-vivo. PA contractility did not change, however significant inhibition of NO-dependent vasodilation was observed that was maximal at 24-48hours post exposure. Superoxide dismutase restored NO-dependent vasodilation suggesting a role for increased superoxide formation. This was supported by ∼2-fold increase in superoxide formation (measured using 2-hydroethidine oxidation to 2-OH-E(+)) from PA isolated from Cl2 exposed rats. We next measured PA pressures in anesthetized rats. Surprisingly, PA pressures were significantly (∼4mmHg) lower in rats that had been exposed to Cl2 gas 24hours earlier suggesting that deficit in NO-signaling observed in isolated PA experiments did not manifest as increased PA pressures in vivo. Administration of the iNOS selective inhibitor 1400W, restored PA pressures to normal in Cl2 exposed, but not control rats suggesting that any deficit in NO-signaling due to increased superoxide formation in the PA, is offset by increased NO-formation from iNOS. These data indicate that disruption of endogenous NO-signaling mechanisms that maintain PA tone is an important aspect of post-Cl2 gas exposure toxicity.

Language: en