Journal of Applied Physiology, Vol 59, Issue 2 354-359, Copyright © 1985 by American Physiological Society
Pulmonary and cardiovascular changes in hyperreactive rats from citric acid aerosols
R. Hamel and A. W. Ford-Hutchinson
Administration of aerosols of citric acid to anesthetized spontaneously
breathing hyperreactive rats produced reversible increases in respiratory
rate (f) and pleural pressure (Ppl) accompanied by hypotension and
bradycardia. In contrast, Fischer rats, which do not have bronchial
hyperreactivity, failed to respond to citric acid aerosols. The effects of
various treatments on citric acid-induced changes in f, Ppl and blood
pressure were studied. Vagotomy, cromolyn sodium (1 and 10 mg/kg iv),
mecamylamine, (2 mg/kg iv), FPL-55712 (3 mg/kg iv), and BW 755C (10 mg/kg
iv) inhibited markedly the responses to citric acid, whereas atropine (2
mg/kg iv) produced weak inhibition. Methysergide (1 mg/kg iv), indomethacin
(1 mg/kg iv), and a prostanoid antagonist, L-640,035, (5 mg/kg iv) were
completely ineffective. The results suggest that citric acid-induced
bronchoconstriction in hyperreactive rats may be reflex mediated and that
leukotrienes may be involved in the response.
