Color Atlas of Pharmacology (Part 10): Nicotine

Nicotine is no longer possible, even in the face of an intensive and synchronized release of ACh (C). Although nicotine mimics the action of ACh at the receptors, it cannot duplicate the time course of intrasynaptic agonist concentration required for appropriate high-frequency ganglionic activation. The concentration of nicotine in the synaptic cleft can neither build up as rapidly as that of ACh released from nerve terminals nor can nicotine be eliminated from the synaptic cleft as quickly as ACh. The ganglionic effects of ACh can be blocked by tetraethylammonium, hexamethonium, and other substances (ganglionic blockers). None of these has intrinsic...