A new rhinitis model using chemical mediators in rats.

No good experimental model for studying rhinitis, has been hitherto available. In the present study, development of a new rhinitis model using chemical mediators was attempted, especially to establish an index of nasal congestion. Male Wistar rats were anesthetized with pentobarbital-Na. Nasal cavities were ventilated between both cannulae inserted into the nasopharynx and bilateral nostrils, with an artificial respirator. Intranasal resistance was recorded with a modification of a Konzett-Rössler apparatus as a change in ventilation overflow (VO). To provoke rhinitis, some mediators were inhaled into the nasal cavities with an ultrasonic nebulizer for 5 min. To assess the capillary permeability of the nasal mucosa, exudation of Evans blue was determined by injecting the dye before inhalations of mediators. Inhalation of histamine (0.01, 0.1, 0.3%), bradykinin (0.01, 0.1%) and ACh (0.3%) markedly increased VO, while inhalation of serotonin (0.01, 0.1, 0.3%) did not increase VO. Histamine, bradykinin and high concentration of ACh significantly increased the dye exudation in the nasal cavities, although serotonin did not. From the above results, it is concluded that 1) a new rhinitis model in which symptoms of nasal blockage and increased capillary permeability in nasal mucosa are quantitatively determined, was established, and 2) histamine- and bradykinin-inhalations can cause rhinitis-like symptoms, although serotonin-inhalation can not.