Nicotinic acetylcholine receptors, muscle-type

Methods for recording the currents through single ion channels were developed by Neher and Sakmann (42)and Hamill et al. (43). The theoretical basis for their interpretation was developed initially by Colquhoun and Hawkes (44,45). Far more is known about the muscle-type nicotinic acetylcholine receptor than about any other. The first attempts to investigate the mechanism of action of acetylcholine (ACh) itself were made by Colquhoun and Sakmann (46,47). By that time it was already... 

The Wild-Type Nicotinic Acetylcholine Receptor (Muscle Type), 373... 

Nicotinic receptors (nicotinic acetylcholine receptors, nACHR) exist not only in the membrane of vertebrate skeletal muscle at the synapse between nerve and muscle (muscle-type nAChR) but also at various synapses throughout the brain, mainly at presynaptic positions (neuronal-type nAChR). Whereas the muscle-type nAChR is precisely composed of two a 1-subunits, one (3 -subunit, one y -subunit and one y -subunit (adult)... 

Acetylcholine (ACh) is an example of an endogenous neurotransmitter that binds to more than one receptor type, the nicotinic acetylcholine receptor (nAChR) which preferentially binds nicotine and the muscarinic receptor which binds muscarine, a mushroom alkaloid. The latter is a G protein-coupled receptor while the nACh receptor is an excitatory ligand-gated ion channel that transports Na-i- ions. Nicotinic cholinergic receptors are found in the CNS, autonomic ganglia, and at the neuromuscular junction of skeletal muscles. They are a possible target for anaesthetics. 

Nicotiana tabacum, and lobeline, present in the dried leaves and tops of the herb, Lobelia inflata (13). Both nicotine and lobeline act as agonists on a specific type of acetylcholine receptor, the nicotinic cholinergic receptor. In mammals, nicotinic cholinergic receptors mediate cholinergic neurotransmission in skeletal muscles, autonomic ganglia, and the central nervous system. At these sites nicotine s action has two phases, excitation and depression. Insect central nervous tissues are rich in nicotinic cholinergic receptors (cf. 14), but their role in behavior is not well understood. 

As we have seen [in a previous chapter], acetylcholine occurs in s niapses in both the somatic and the autonomic nervous system. The nicotinic acetylcholine receptor is found in the motor endplate of the skeletal muscle, and in both the sympathetic and the parasympathetic ganglia of the peripheral autonomic system. Muscarinic acetylcholine receptors are found at the endings of all secondary neurons within the parasympathetic part of the peripheral autonomous system. In addition, acetylcholine receptors of both types also occur in the brain. Drugs with a useful degree of selectivity for each of these targets are available and used in practical medicine. Selectivity is based on two principles ... 

From these results it was concluded that there was one type of acetylcholine receptor on skeletal muscles and at nerve synapses (the nicotinic receptor), and a different sort of acetylcholine receptor on smooth muscle and cardiac muscle (the muscarinic receptor). 

As we learned in Chapter 7, many neurotransmitter receptors are ligand-gated ion channels. These Include some types of glutamate and serotonin receptors, as well as the nicotinic acetylcholine receptor found at nerve-muscle synapses. Many... 

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