Figure 27-21 Antihypotensive drugs such as metaraminol (Aramine), tyramine, and ephedrine create their effect by releasing catecholamines from the granules of the nerve terminal. Therefore, when treatment with drugs such as methyldopa, reserpine, or guanethidine depletes the store of norepinephrine (NE) in the granules, little NE remains for release, and the antihypotensive drugs have been rendered ineffective.