Bromocriptine-induced decrease in blood pressure in conscious spontaneously hypertensive rats: evidence for a peripheral site of action.

The aim of the study was to discover whether the dopamine agonist bromocriptine has a central or peripheral site of action on blood pressure. An intraperitoneal injection of bromocriptine (0.5 mg kg-1) induced a long-lasting decrease in blood pressure in conscious spontaneously hypertensive rats (SHR). This effect was blocked by peripheral pretreatment with haloperidol or domperidone, but not by central treatment with haloperidol. A central injection of bromocriptine had only minor effects on blood pressure. These results suggest that primarily peripheral, rather than central, mechanisms are involved in the hypotensive effects of bromocriptine.