Substitute, or false, transmitters are compounds which replace norepinephrine (the normal transmitter) in adrenergic nerve endings end which are released by nerve stimulation. Adrenergic function may be depressed by a substitute transmitter if the substitute is less potent than norepinephrine on adrenergic receptors. It is currently believed that methyldopa exerts its antihypertensive effect by this mechanism. Metaraminol may also serve as a substitute transmitter, and the drug can be shown to have antihypertensive properties in man under certain conditions. The antihypertensive effect of monoamine oxidase inhibition may also be mediated by a substitute-transmitter mechanism.
- © 1966 American Heart Association, Inc.