Relationship between density of muscarinic receptors and nasal hypersecretion in a nasal allergic model.

In guinea pigs actively sensitized with ovalbumin, we have observed that nasal hyperreactivity and hypersensitivity to methacholine causes nasal secretion accompanied by an increase in the density of muscarinic acetylcholine receptor (m-ACh.R) following the appearance of nasal symptoms induced by the ovalbumin challenge. Therefore in the present investigation, we studied the relationship between the density of m-ACh.R and nasal hypersecretion in actively sensitized guinea pigs. There was no relationship between the quantity of nasal secretion and serum Ig G1 or Ig E levels. On the other hand, the sensitivity to methacholine and nasal secretion induced by methacholine were significantly related to the density of m-ACh.R located on the nasal mucosa. The quantity of nasal secretion induced by allergen was also correlated significantly to the density of m-ACh.R. These results suggest that the nasal hypersecretion observed in the nasal allergic model may be closely associated with an increase in the density of m-ACh.R located on the nasal mucosa.