REDUCTION OF RESPONSES TO ANGIOTENSIN-II BY ANTIDEPRESSANT DRUGS

The effects of the antidepressant drugs desipramine, fluoxetine and tr anylcypromine and the non-antidepressant control cocaine on angiotensi n II function were determined in vivo by use of angiotensin-induced dr inking in rats and in vitro using contractile responses of the rat ute rus. The results of the drinking studies showed that the three antidep ressants, but not cocaine, reduced the dipsogenic effects of angiotens in II. In vitro, all of the drugs reduced the effects of not only angi otensin but also acetylcholine and oxytocin on the uterus. The inhibit ion appeared to be non-competitive in all cases. These results indicat e that the antidepressant drugs reduced the activity of angiotensin II , albeit non-selectively, and suggest that the previously reported eff ects of antidepressants on isoprenaline-induced drinking in rats refle ct an action on angiotensin activity rather than a reduction of beta-a drenoceptor activity as previously suggested.