Journal of Applied Physiology, Vol 55, Issue 6 1803-1810, Copyright © 1983 by American Physiological Society
Response of bronchial smooth muscle to mast cell degranulation in situ
E. R. Garrity, N. P. Stimler, N. M. Munoz, R. Fried and A. R. Leff
We studied the response of bronchial smooth muscle to mast cell
degranulation with Ascaris suum antigen (AA) and compound 48/80 (48/80) in
26 mongrel dogs in situ. Bronchial smooth muscle response was measured
isometrically in situ from a segment of the right middle lobe bronchus;
tracheal response was monitored isometrically as a control. After
intra-arterial (ia) injection of AA into the bronchial circulation,
bronchial contraction preceded tracheal contraction by 19.2 +/- 4.6 s (P
less than 0.002). Bronchial contraction to AA (21.7 +/- 3.4 g) was
substantially greater than to 48/80 (10.5 +/- 1.8 g, P less than 0.05)
corresponding to differences in maximal systemic histamine concentrations
(146 +/- 24.1 vs. 1000 +/- 236 ng/ml, P less than 0.01). In 5 dogs, the
effect of leukotriene D4 (LTD4) and FPL 55712 was studied. Injection of
10(-8) mol ia LTD4 caused no bronchial contraction. In four dogs, 10(-7)
mol FPL 55712 caused no bronchial relaxation after initial precontraction
during immune degranulation with AA; intravenous chlorpheniramine (5 mg/kg)
caused 69.7 +/- 9.4% relaxation. We demonstrate a model that permits
selective immune degranulation of a single major resistance bronchus in
situ. We conclude that AA-induced degranulation in dogs caused bronchial
contraction predominantly by secretion of preformed mediator.
