Research

Changes in the expression of NO synthase isoforms after ozone: the effects of allergen exposure

An-Soo Jang¹ , Inseon-S Choi² , Jong-Un Lee³ , Sung-Woo Park¹ , June-Hyuk Lee¹ and Choon-Sik Park¹

¹  Department of Internal Medicine, Soonchunhyang University Hospital, Bucheon, 1174, Jung-dong, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-767 Republic of Korea

²  Research Institute of Medical Sciences, Department of Internal Medicine, Chonnam National University, 8, Hak-1-dong, Gwangju, 501-757, Republic of Korea

³  Physiology, Chonnam National University Medical School, Chonnam National University, 5, Hak-1-dong, Gwangju, 501-757, Republic of Korea

author email corresponding author email

Respiratory Research 2004, 5:5doi:10.1186/1465-9921-5-5

Published:	5 June 2004

Abstract

Background

The functional role of nitric oxide (NO) and various nitric oxide synthase (NOS) isoforms in asthma remains unclear.

Objective

This study investigated the effects of ozone and ovalbumin (OVA) exposure on NOS isoforms.

Methods

The expression of inducible NOS (iNOS), neuronal NOS (nNOS), and endothelial NOS (eNOS) in lung tissue was measured. Enhanced pause (P_enh) was measured as a marker of airway obstruction. Nitrate and nitrite in bronchoalveolar lavage (BAL) fluid were measured using a modified Griess reaction.

Results

The nitrate concentration in BAL fluid from the OVA-sensitized/ozone-exposed/OVA-challenged group was greater than that of the OVA-sensitized/saline-challenged group. Methacholine-induced P_enh was increased in the OVA-sensitized/ozone-exposed/OVA-challenged group, with a shift in the dose-response curve to the left, compared with the OVA-sensitized/saline-challenged group. The levels of nNOS and eNOS were increased significantly in the OVA-sensitized/ozone-exposed/OVA-challenged group and the iNOS levels were reduced compared with the OVA-sensitized/saline-challenged group.

Conclusion

In mice, ozone is associated with increases in lung eNOS and nNOS, and decreases in iNOS. None of these enzymes are further affected by allergens, suggesting that the NOS isoforms play different roles in airway inflammation after ozone exposure.