Modulation of bronchial smooth muscle function in horses with heaves

muscle function in horses with heaves. J. Appl. Physiol. 77(5): 2149-2154, 1994.-Four mechanisms that modulate airway smooth muscle function in normal horses were studied in the bronchi of horses affected by the airway obstructive disease heaves. Results were compared with data from historical con-trols studied by the same personnel in the same laboratory. Rings from the left cranial lobar bronchus (LBl) and small bronchi (5 mm OD) were suspended in muscle baths, and the isometric tension was measured. The inhibitory nonadrenergic noncholinergic (iNANC) function was studied in LBl. After the LB1 segments were pretreated with atropine and con-tracted with histamine, electrical field stimulation (EFS) in-duced little or no relaxation, indicating iNANC dysfunction in horses with heaves. Bronchi from animals with heaves were hyporesponsive to EFS and acetylcholine. Epithelial remova