Distribution of substance P binding sites in equine airways.
Autoradiography with [125I]-Bolton Hunter substance P ([I]-BHSP) was used to detect substance P binding sites in the equine lung. Specific [I]-BHSP binding sites were very dense over small bronchial vessels, tracheobronchial glands and airway epithelium in large and small airways. The density of [I]-BHSP binding sites over airway smooth muscle was much lower than in the preceding tissues. Competition with an excess of either a specific neurokinin 1 receptor agonist, or a specific neurokinin 2 receptor agonist indicated that most specific [I]-BHSP binding sites in the equine lung represent neurokinin 1 receptors. The receptor-mediated effects of substance P in the equine lung are most likely to involve regulation of vascular tone and airway secretions based upon the density of specific [I]-BHSP binding sites in these tissues. Activation of intrapulmonary afferent nerves containing Substance P by noxious stimuli such as inhaled allergens or irritants may lead to increased mucus secretion and decreased airway diameter due to vascular congestion.
Sonea
I M
IM
Department of Anatomy, College of Veterinary Medicine, Michigan State University, East Lansing 48823, USA.
Bowker
R M
RM
Robinson
N E
NE
D000818:Animals; D001345:Autoradiography / Q000662:veterinary; D001665:Binding Sites; D001980:Bronchi / Q000378:metabolism*; D003720:Densitometry / Q000662:veterinary; D005260:Female; D006736:Horses / Q000378:metabolism*; D008297:Male; D013373:Substance P / Q000378:metabolism*
D013373:Substance P