Alcohol effects on the 5-HT3 ligand-gated ion channel.

1. Alcohols and volatile anesthetics have both potentiating and channel blocking effects on members of the nicotinic ACh-like subfamily of ligand-gated ion channels. 2. The alcohol and anesthetic sensitivity of the 5-HT3 receptor, a member of this receptor subfamily, has been examined extensively by several laboratories. 3. Alcohols and volatile anesthetics potentiate receptor function. 4. This potentiation is characterized by an increase in the apparent potency with which agonists activate the receptor, and an apparent stabilization and favoring of the open channel state. 5. Long-chain alcohols and trichloroethanol also inhibit channel function, perhaps through a channel blocking mechanism similar to that seen at the nACh receptor. 6. Studies of the relationship between receptor structure and alcohol and anesthetic effects are just beginning, but some clues from other members of this subfamily of ligand-gated channels may help to pinpoint areas of the receptor that are important for alcohol effects.