How does succinylcholine affect the muscles?

Succinylcholine is a neuromuscular blocker that acts as a depolarizing agent at the neuromuscular junction. When administered, it binds to nicotinic acetylcholine receptors on the motor end plate of the muscle fibers, leading to an initial depolarization of the muscle membrane. This process causes a brief muscle contraction, often referred to as fasciculations, followed by paralysis.

The key aspect of succinylcholine's action is its ability to remain bound to the acetylcholine receptors, which prevents them from repolarizing. This mechanism effectively inhibits further muscle contraction, resulting in a state of paralysis, but the defining action is the initial depolarization it causes. The other options, while related to muscle function in various ways, do not accurately describe how succinylcholine exerts its primary effect on muscle fibers.