ABSTRACT
Irritation of the rodent airway mucosa initiates local reflexes that induce vasodilatation and increased vascular permeability. Electrical stimulation of vagal nerves, intratracheal capsaicin, and intravenous substance P induce mucosal edema formation and movement of plasma proteins into the lumens of tracheobronchial airways, indicating that neurogenic inflammation involves increased vascular and epithelial permeability for plasma proteins. This hypothesis was tested by assessing the distribution and identities of leaking vessels and morphological changes in epithelial cells generated following electrical stimulation of the vagal nerves in rat airways. After the electrical vagal stimulation (EVS), animals were sacrificed by exsanguination, the airways were dissected, and the tissue was processed for light or electron microscopy. The epithelial secretory cells were contracted and degranulated with few granules remaining within the cytoplasm. The movement of plasma proteins from vessels, through the interstitial spaces, and across the epithelium was traced by following the extravasation of intravenously injected I-bovine serum albumin by autoradiography.
