Modulation of neurogenic inflammation in rat trachea.

Antidromic stimulation of the cervical vagus nerve in anaesthetised rats resulted in plasma protein extravasation in the trachea. This response was potentiated significantly by pretreatment of the animals with an enkephalinase inhibitor, thiorphan (100 micrograms/kg). Exposure of animals to ozone (5-6 ppm) for 30 min caused a significant increase in the numbers of lung lavage epithelial cells but failed to potentiate neuronally-evoked tracheal oedema. Several compounds were investigated for anti-permeability effects on thiorphan-pretreated, nerve stimulated animals. Morphine (3 mg/kg) and salbutamol (100 micrograms/kg) were the most efficacious agents used and resulted in 66 +/- 14% and 61 +/- 9% inhibition of tracheal oedema, respectively. Sodium cromoglycate at 30 mg/kg produced a small but significant reduction in oedema (34 +/- 10%). Dexamethasone (3 mg/kg), methysergide (2 mg/kg) and theophylline (10 mg/kg) did not affect neurogenic oedema.