Flunixin meglumine blocks frusemide-induced bronchodilation in horses with chronic obstructive pulmonary disease.
Six horses that developed acute airway obstruction (heaves) when housed in a barn and fed poor-quality hay were studied. Airway obstruction was verified by a maximal change in pleural pressure during tidal breathing (delta Pplmax) of at least 15 cmH2O. Frusemide (1.0 mg/kg bwt) or an equivalent volume of vehicle was then administered intravenously (iv) and lung function was measured 15, 30, 60, 120, 180, 240 and 300 mins after drug administration. The effect of frusemide on lung function was also studied after treatment of horses with the cyclooxygenase inhibitor flunixin meglumine (1.1 mg/kg every 8 h for 2 days before the experiment). Frusemide significantly reduced the delta Pplmax beginning 15 mins after drug administration. This effect persisted for 5 h. The reduction in delta Pplmax was due partly to an increase in dynamic compliance and partly to a decrease in pulmonary resistance. Tidal volume and respiratory frequency were unaffected by frusemide. Vehicle had no effect on lung function. Flunixin meglumine abolished the effect of frusemide on airway calibre but did not prevent diuresis. These results indicate that the effect of frusemide on airways of horses with heaves persists for at least 5 h, is mediated through prostanoids, and is not a result of diuresis.
Rubie
S
S
Pulmonary Laboratory, College of Veterinary Medicine, Michigan State University, E. Lansing 48824.
Robinson
N E
NE
Stoll
M
M
Broadstone
R V
RV
Derksen
F J
FJ
D000704:Analysis of Variance; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D016084:Bronchoconstriction / Q000187:drug effects*; D003002:Clonixin / Q000031:analogs & derivatives* / Q000494:pharmacology; D005665:Furosemide / Q000037:antagonists & inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D006734:Horse Diseases / Q000188:drug therapy / Q000503:physiopathology*; D006736:Horses; D008168:Lung / Q000187:drug effects / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000188:drug therapy / Q000503:physiopathology / Q000662:veterinary*; D012119:Respiration / Q000187:drug effects; D013990:Tidal Volume / Q000187:drug effects
D000894:Anti-Inflammatory Agents, Non-Steroidal; D005665:Furosemide; C014558:flunixin meglumine; D003002:Clonixin