Substance P and nasal secretion in dog, rat, and man

The effect of substance P (SP) on nasal secretion was studied in dog, rat, and man. Substance P was administered topically by the use of filter papers that had been soaked with an aqueous solution of SP and dried. The SP-containing filter paper strips were applied to the nasal mucosa for five minutes. The secretion was absorbed onto the filter papers. The strips were weighed before and after the experiment. Substance P induced atropine-resistant nasal secretion in a dose-dependent manner in anaesthetized dogs and rats. In man, SP failed to evoke nasal secretion in the doses applied. Systemic effects limited the dose that could be given to man. When exposed to nasal secretions SP was rapidly degraded. This may explain the failure of SP to evoke nasal secretion in man.