Hyperpnea-induced production of TBHP-initiated chemiluminescence in guinea pigs.

Antioxidants attenuate hyperpnea-induced airway constriction. It was hypothesized that this type of airway constriction is closely related to reactive oxygen species (ROS). However, there is no direct evidence of an increase in ROS during or right after the course of hyperpnea. To detect ROS production induced by hyperpnea, forty one guinea pigs were divided into four groups: control; control with 95% O2-5% CO2; hyperpnea with 95% air-5% CO2; and hyperpnea with 95% O2-5% CO2. Three minutes following hyperpnea or at the equivalent time, we obtained bronchoalveolar lavage (BAL) and measured its chemiluminescence (CL) counts. In addition, hyperpnea with 95% O2-5% CO2 gas mixture was carried out and BAL was collected 3 minutes after the hyperpnea in an additional forty animals. We measured CL counts in BAL samples before and after the treatments of the following ROS scavenger(s) or saline in vitro: control (saline); superoxide dismutase (SOD); catalase; dimethylthiourea (DMTU); and SOD+catalase+DMTU. Hyperpnea with 95% O2-5% CO2, but not with 95% air-5% CO2, gas mixture induced significant increase in t-butyl hydroperoxide-initiated CL counts, which were inhibited by DMTU, catalase, or SOD in vitro. Our data suggest that hyperpnea with a 95% O2-5% CO2, but not with 95% air-5% CO2, gas mixture induced an increase in ROS production.