| Receptor | Enzyme coupling (via G-protein) |
Second messenger |
Effectors |
| Alpha-1 |
Phospholipase C | IP2 + DAG | Activation of protein kinases |
| Alpha-2 |
Inhibition of adenyl cyclase | Reduced cAMP | |
| Beta 1/Beta 2 |
Stimulation of adenyl cyclase | Increased cAMP | Activation of protein kinases |
| Muscarininc | |||
| Nicotinine |
- Direct ion channel linkage |