Acetylcholin Receptor, nicotinic Gating mechanism

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Carbamazepine is both an important anticonvulsant in therapeutic doses and a powerful proconvulsant in overdose. The therapeutic anticonvulsant mechanism is primarily related to blockade of presynaptic voltage-gated sodium channels. Blockade of the sodium channels is believed to inhibit the release of synaptic glutamate and possibly other neurotransmitters. Carbamazepine is also a powerful inhibitor of the muscurinic and nicotinic acetylcholine receptors, N-methyl-D-aspartate (NMDA) receptors and the central nervous system (CNS) adenosine receptors. In addition, carbamazepine is structurally related to the cyclic antidepressant impramine and in massive overdose may affect cardiac sodium channels. 

Ion channels (center). These receptors contain ligand-gated ion channels. Binding of the signaling substance opens the channels for ions such as Na, Ca, and Cl . This mechanism is mainly used by neurotransmitters such as acetylcholine (nicotinic receptor see p.224) and GABA (A receptor see p.354). 

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