Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, and it blocks HCN1 receptors. However, at higher doses it may also bind to the opioid mu and sigma receptors. It disrupts the neurotransmitter (brain chemical) glutamate. Glutamate is involved with learning, memory, emotion, and pain recognition. It can exhibit sympathomimetic activity which can lead to rapid heart rate and elevated blood pressure