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Journal of Environmental Pathology, Toxicology and Oncology

ISSN for PRINT: 0731-8898

Institutional price:	$672.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2006, Volume25

82 pages

Issue price - $172.00

Inhibition of Prostacyclin Release by Cigarette Smoke Extract in Endothelial Cells is not Related to Enhanced Superoxide Generation and NADPH-Oxidase Activation

M. Mahfouz
The H. E. Moore Heart Research Foundation, Champaign, IL, USA

Zhou Qi
Burnsides Research Laboratory, University of Illinois, Urbana, IL, USA

F. A. Kummerow
The H. E. Moore Heart Research Foundation, Champaign; and Burnsides Research Laboratory, University of Illinois, Urbana, IL, USA

ABSTRACT

Exposure of human umbilical endothelial cells (ECs) to cigarette smoke extract (CSE) activated the NADPH-oxidase enzyme and increased the production of superoxide (O⁻₂) as well as reactive oxygen species (ROS). CSE also inhibited the prostacyclin (PGI₂) formation by ECs. Preincubation of ECs with diphenylene iodonium (DPI), the inhibitor of NADPH oxidase, blocked the increase of O⁻₂ production, but neither lowered the ROS level nor prevented the inhibition of PGI₂ formation in CSE-treated cells. Preincubation of ECs with a medium supplemented with 1 mM vitamin C did not decrease, but rather increased the O⁻₂ production in CSE-treated cells. However, adding 1 mM glutathione (GSH) to vitamin C decreased the O⁻₂ production, indicating that vitamin C was overwhelmed by the prooxidant in CS, and GSH enhanced the recycling process and spared vitamin C. The ROS level remained high in CSE-treated cells even after preincubation with vitamin C or vitamin C + GSH compared to the control cells. These results are discussed in light of the possible decrease of antioxidant enzyme activities in CSE-treated cells and the increase of cellular hydrogen peroxide (H₂O₂) generated from the CSE, which cause an imbalance between oxidizing species and the antioxidants producing oxidative stress in CSE-treated cells. These results demonstrate that CSE has a direct inhibitory effect on PGI₂ formation and enhances the level of ROS in CSE-treated ECs, regardless of the activation of NADPH-oxidase.