This study investigated the relationship between
oxygen radicals and
exsanguination-induced bronchoconstriction using
antioxidant in guinea pigs. To accomplish this, two phases of studies were carried out. In phase 1, 34 guinea pigs weighing 342 +/- 11 g were divided into five groups: control (n = 7); acute
dimethylthiourea (
DMTU, n = 7); chronic
DMTU (n = 8);
superoxide dismutase (SOD, n = 6); and
catalase (n = 6). Animals in the control group were not treated.
DMTU, SOD, and
catalase were employed for the scavenging of
hydroxyl radical,
superoxide anion, and
hydrogen peroxide, respectively. Ten additional guinea pigs weighing 293 +/- 6 g were divided into two groups in phase 2:
sham (n = 6) and chronic
apocynin (n = 4). Animals in the
sham group received
injections of the vehicle, whereas
apocynin was used to suppress the production of
superoxide anion. All animals were anesthetized, sternotomized, and artificially ventilated. Before (baseline) as well as at fixed intervals 5-30 minutes following the
exsanguination, the maximal expiratory flow maneuver was performed and the dynamic compliance (Cdyn) was obtained. Decreases in the maximal expiratory flow at 50% baseline vital capacity and Cdyn were used as indicators of bronchoconstriction.
Exsanguination in the control and
sham groups caused a gradual increase in airway constriction with time that was significantly ameliorated by chronic
DMTU and chronic
apocynin pretreatments but was not affected by other acute treatments. These results indicate that chronic treatment with
antioxidants ameliorates
exsanguination-induced,
tachykinin-mediated airway constriction.