Increased density of substance P binding sites in specific brainstem nuclei of spontaneously hypertensive rats.

Substance P binding sites were quantitated in 16-week-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto rats by incubation of brain sections with 125I-Bolton-Hunter substance P, autoradiography and microdensitometry. The maximum binding capacity (Bmax) was significantly increased in the dorsal motor nucleus of the vagus, in the hypoglossal, ambiguus and inferior olivary nuclei, and in lobes 9 and 10 of the vermis cerebelli of SHR.