INHIBITION OF CARDIAC BAROREFLEX SENSITIVITY AFTER CENTRAL DOPAMINERGIC STIMULATION

1. Stimulation of the mesolimbic dopamine system, by microinjection of the substance P analogue [pGlu(5),MePhe(8),Sar(9)]substance P (DiMe-C 7) into the ventral tegmental area induced a prolonged increase in blo od pressure and circulating levels of vasopressin. 2. In the present s tudy, this treatment produced a significant decrease of cardiac barore flex sensitivity in conscious rats. After pretreatment with the dopami ne receptor antagonist raclopride, central stimulation failed to produ ce any changes in baroreflex parameters. 3. The central dopamine-media ted decrease in baroreflex sensitivity may be involved in functionally potentiating the circulatory actions of vasopressin.