The pharmacology of pramipexole in the spontaneously hypertensive rat.

Pramipexole (SND-919) administration to spontaneously hypertensive rats resulted in a biphasic response with lower doses (1-30 micrograms/kg) causing a hypotensive response and higher doses (100-1000 micrograms/kg) increasing blood pressure. S-Sulpiride (1 mg/kg i.v.) and domperidone (100 micrograms/kg i.v.) but not SCH 23390(1 microgram/kg per min i.a.), prazosin (0.1 mg/kg i.v.) or rauwolscine (1 mg/kg i.v.) blocked the depressor effect, whereas rauwolscine but not S-sulpiride, SCH 23390 or prazosin blocked the pressor effects. The data indicate that pramipexole stimulates presynaptic DA2 receptors at low doses and postsynaptic alpha 2-receptors at high doses.