NIGROSTRIATAL DOPAMINE SYSTEM MEDIATES BAROREFLEX SENSITIVITY IN RATS

Both sham-operated rats and rats with lesions of the nigrostriatal dop amine (DA) pathway were subjected to increasing or decreasing carotid sinus pressure (respectively produced by phenylephrine injection or bi lateral carotid occlusion) and their striatal DA release and barorefle x responses were compared. In sham-operated rats, phenylephrine produc ed both increased striatal DA release and decreased heart rate, while bilateral carotid occlusion produced the apposite effects. Both the st riatal DA release and baroreflex responses produced by phenylephrine o r carotid occlusion were attenuated by lesions of the nigrostriatal DA pathway induced by intra-medial forebrain bundle injection of 6-hydro xydopamine. The data indicate that the nigrostriatal DA pathway mediat es baroreflex sensitivity in rats.