Receptors
Receptors can be divided into metabotropic and ionotropic subtypes.
When activated an ionotropic receptor mediates its effect by opening an ion channel on the surface of a cell.
Metabotropic (G-protein) receptors are linked to G proteins which when activated imitates a reaction within the cell.
The effects of ionotropic receptors are generally very short lived where as the effects of metabotropic receptors are generally longer.
The effect of ionotropic receptors is instant where as they are slightly delayed in metabotropic receptors.
The effects of ionotropic receptors are quite specific compared to metabotropic effects which are often diffuse.
The following table lists some important terms used when discussing drugs and receptors.
| Ionotropic receptors | Metabotropic receptors |
|---|---|
| GABA-A | GABA-B |
| 5HT-3 | Serotinergic receptors (except 5HT-3) |
| Nicotinic acetylcholine receptors | Muscarinic acetylcholine receptors |
| Glutaminergic (NMDA) | Dopaminergic |
| Glycine | Adrenergic |
When activated an ionotropic receptor mediates its effect by opening an ion channel on the surface of a cell.
Metabotropic (G-protein) receptors are linked to G proteins which when activated imitates a reaction within the cell.
The effects of ionotropic receptors are generally very short lived where as the effects of metabotropic receptors are generally longer.
The effect of ionotropic receptors is instant where as they are slightly delayed in metabotropic receptors.
The effects of ionotropic receptors are quite specific compared to metabotropic effects which are often diffuse.
The following table lists some important terms used when discussing drugs and receptors.
| Affinity | how avidly the drug binds to the receptor |
|---|---|
| Potency | the concentration or dose of a drug required to produce 50% of the drug's maximal effect. Potency depends on both the affinity of a drug for its receptor, and the efficiency with which drug-receptor interaction is coupled to response |
| Efficacy | also referred to as 'intrinsic activity' of a drug is the ability of the drug to elicit a response when it binds to the receptor |
