Vascular permeability increased by histamine aerosol, capsaicin, and electric stimulation of vagus nerves in guinea pigs

The present study was to clarify the tissue differences in vascular permeability enhanced by 0.1% histamine aerosol, capsaicin (50 micrograms.kg-1, iv), and electric stimulation of vagus nerves (ESV, 12 V, 5 ms, 16 Hz, for 90 s) in different parts of airways, heart, esophagus, ileum, kidney, and liver of guinea pigs using Evans blue (30 mg.kg-1, iv) as a tracer. All the treatments significantly increased the dye extravasation in trachea, main bronchi, proximal and distal intrapulmonary airways (by 64-722%), as well as in the heart (by 89-126%), most remarkable for capsaicin on trachea and main bronchi. Capsaicin also markedly increased the dye content in esophagus. These results demonstrate that neurogenic inflammation induced by capsaicin and ESV primarily increases vascular permeability in the respiratory tract and heart.