Measurement of ascorbic acid concentration and glutathione peroxidase activity in biological samples collected from horses with recurrent airway obstruction.
OBJECTIVE
To measure the ascorbic acid (AA) concentration in bronchoalveolar lavage fluid (BALF) and cellular glutathione peroxidase (cGPx) activity in RBCs and WBCs from peripherally obtained blood and in cells from BALF to determine whether differences existed between the 2 major redox systems in recurrent airway obstruction (RAO)-affected and -nonaffected (control) horses and between systemic and local pulmonary responses in the glutathione redox system.


METHODS
16 adult horses in pairs: 8 healthy (control) and 8 RAO-affected horses.


METHODS
Physical examination data and biological samples were collected from horses before (remission), during, and after (recovery) environmental challenge with dusty straw and hay. At each stage, BALF cell AA concentration and RBC, WBC, and BALF cell cGPx activity were measured.


RESULTS
Compared with control horses, RAO-affected horses had significantly higher cGPx activity in RBCs at all points and in WBCs during remission and challenge. The BALF cell cGPx activity was higher in RAO-affected horses during recovery than during remission The BALF cell AA concentration did not differ significantly in control horses at any point, but total and free AA concentrations were significantly lower in RAO-affected horses during the challenge period than during remission and recovery periods.


CONCLUSIONS
High cGPx activity suggested this redox system was upregulated during exposure to dusty straw and hay to combat oxidative stress, as AA was depleted in RAO-affected horses. The relative delay and lack of comparative increase in cGPx activity within the local environment (represented by BALF cells), compared with that in RBCs and WBCs, might contribute to disease in RAO-affected horses.
Department of Veterinary Clinical Sciences, School of Veterinary and Biomedical Sciences, James Cook University, Townsville, QLD 4810, Australia. tanr@vt.edu
Rachel H H
RH
Tan
Craig D
CD
Thatcher
Virginia
V
Buechner-Maxwell
Undine
U
Christmann
Mark V
MV
Crisman
Stephen R
SR
Werre
D000402:Airway Obstruction / Q000097:blood / Q000201:enzymology / Q000517:prevention & control / Q000662:veterinary*; D000818:Animals; D001205:Ascorbic Acid / Q000032:analysis*; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry*; D004912:Erythrocytes / Q000201:enzymology*; D005979:Glutathione Peroxidase / Q000097:blood*; D006734:Horse Diseases / Q000097:blood* / Q000201:enzymology / Q000517:prevention & control; D006736:Horses; D012008:Recurrence; D012016:Reference Values
D005979:Glutathione Peroxidase; D001205:Ascorbic Acid