Ionotropic receptor sodium channels

Non-NMDA ionotropic glutamate receptors (the majority sodium channel containing) can be subdivided into a-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) (comprising cloned subunits GluRl ) and kainate (GluR5-7, KAl-2) preferring receptors, with native receptors most likely to comprise either homo- or heteromeric pentamers of these subunits. 

Neurotransmitters can either excite or inhibit the activity of a cell with which they are in contact. When an excitatory transmitter such as acetylcholine, or an inhibitory transmitter such as GABA, is released from a nerve terminal it diffuses across the synaptic cleft to the postsynaptic membrane, where it activates the receptor site. Some receptors, such as the nicotinic receptor, are directly linked to sodium ion channels, so that when acetylcholine stimulates the nicotinic receptor, the ion channel opens to allow an exchange of sodium and potassium ions across the nerve membrane. Such receptors are called ionotropic receptors. 

Mode of action. The precise mode of action of carbamazepine has not been fully established. It has been shown to stabilize both pre- and postsynaptic neurons by blocking the use and frequency-dependent sodium channels. While this is probably its main action, the blockade of the glutamate NMDA ionotropic receptors also leads to a reduction in the influx of sodium and calcium ions into the neuron. The net effect of these changes is a reduction in the sustained high-frequency repetitive firing of the action potentials which characterize epileptic activity. There is also evidence that carbamazepine blocks purine, noradrenaline, serotonin and muscarinic acetylcholine receptors which probably accounts for the use of carbamazepine as a mood stabilizing agent. 

Lingueglia E, Deval E, Lazdunski M. FMRFamide-gated sodium chatmel and ASIC channels a rtew class of ionotropic receptors for FMRFamide and related peptides. Peptides. 2006 27 1138-52. 

Spider Peptides High molecular weight proteins Polyamines Selective action on voltage-dependent sodium, potassium and calcium channels Induction of neurotransmitter release Antagonists of ionotropic glutamate receptors Enzyme-linked immunosorbent assay 10-20 ngmr ... 

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