What type of receptor does ketamine act upon as an anesthetic?

Ketamine primarily acts as an NMDA receptor antagonist. NMDA receptors are a type of glutamate receptor that play a crucial role in excitatory neurotransmission in the central nervous system. By blocking these receptors, ketamine inhibits the action of glutamate, which can lead to anesthetic effects. The antagonism of NMDA receptors induces a dissociative state, providing effective anesthesia, pain relief, and even some antidepressant effects at subanesthetic doses.

The other receptor types mentioned do not accurately describe how ketamine exerts its anesthetic properties. For instance, dopamine receptor antagonism would typically be associated with effects related to antipsychotic medications, while GABA receptor agonism relates to benzodiazepines and barbiturates, which enhance inhibitory neurotransmission. The alpha-2 adrenergic receptor agonists are implicated in sedation and analgesia through different mechanisms involving noradrenergic pathways.

Thus, the specific action of ketamine on NMDA receptors is what makes it a unique anesthetic, allowing for its distinct pharmacological profile and therapeutic uses.