Besides norepinephrine, the adrenergic system uses:

1. A second signalling molecule is named. 2. It is the same as adrenaline. 3. There is a second signaling molecule called epinephrine. 4. So the answer is epinephrine. _Source: OpenStax 'Anatomy and Physiology 2e', Ch 15 'The Autonomic Nervous System'_