Airway mucosal blood flow: response to autonomic and inflammatory stimuli.

A major portion of airway blood flow is distributed to the subepithelial tissue space and is strategically located to influence both epithelial and airway smooth muscle functions. To assess the magnitude and responsiveness of blood flow through the subepithelial microvasculature, we measured tracheal mucosal blood flow with a soluble gas method in intact sheep. We found responses of tracheal mucosal blood flow to pharmacological stimuli alpha- and beta- (adrenoceptor agonists) and inflammatory stimuli (antigen and histamine), and demonstrated that alterations in mucosal blood flow influence the magnitude and duration of allergic airway smooth muscle contraction in the trachea. Mucosal blood flow, which under certain circumstances is regulated independently of total airway blood flow, could play a critical role in the manifestations of and recovery from airway disease.