EFFECT OF ANGIOTENSIN-II ON STRIATAL DOPAMINE RELEASE IN THE SPONTANEOUS HYPERTENSIVE RAT

We have previously demonstrated that angiotensin II stimulates the rel ease of dopamine from the normotensive rat striatum via the AT(1) rece ptor. In this study, the effect of angiotensin II-stimulated striatal dopamine release in the spontaneous hypertensive rat was compared to n ormotensive controls. In the spontaneous hypertensive rat, angiotensin II stimulated dopamine release to 169+/-13% (P<0.05) in the experimen tal period, with levels remaining high in the recovery phase, 158+/-16 % (P<0.05). This effect was not significantly different from the respo nse in normotensive controls, in which angiotensin II stimulated dopam ine release to 149+/-18% (P<0.05) in the experimental period, with the effect also persisting through the recovery period, 244+/-62% (P<0.05 ). Thus, despite reports of increased activity of the brain angiotensi n II and dopamine systems in the spontaneous hypertensive rat, there i s no evidence of abnormal regulation of the striatonigral dopamine sys tem.