- The nicotinic ACh receptor is also a Na+ and K+ ion channel.
- Binding of ACh to a subunits of the receptor causes a conformational change that opens the central core of the channel and increases its conductance to Na+ and K+. These are examples of ligand-gated channels.
Table 1-2. Agents Affecting Neuromuscular Transmission
Blocks release of ACh from presynaptic terminals
Competes with ACh for receptors on motor end plate
Effect on Neuromuscular Transmission
Decreases size of EPP; maximal doses produce paralysis of respiratory muscles and death
Hemicholinium Blocks reuptake of choline into presynaptic terminal
Prolongs and enhances action of ACh at muscle end plate
Depletes ACh stores from presynaptic terminal
ACh = acetylcholine; EPP = end plate potential.
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