What mechanism of action does Succinylcholine have on muscle fibers?

Succinylcholine primarily acts as a depolarizing neuromuscular blocker. It binds to nicotinic acetylcholine receptors on the motor end plate of muscle fibers, leading to an initial depolarization, which is often followed by a brief period of muscle twitching known as fasciculation. This is essentially a temporary stimulation of the muscle fibers.

After this initial stimulation, Succinylcholine remains bound to the acetylcholine receptors, preventing acetylcholine from binding. This prolonged presence leads to desensitization of the receptors, resulting in a state where the muscle cannot respond to further stimulation. Therefore, the overall effect is a temporary paralysis of the muscle, which is why Succinylcholine is commonly used in medical settings for rapid intubation and during surgical procedures.

The other answer choices do not accurately describe the mechanism of action of Succinylcholine. While dopamine receptors are involved in other neurological processes, they are not relevant to the action of this muscle relaxant. Additionally, the roles of neuraminidase and calcium release do not pertain to the core mechanism by which Succinylcholine exerts its effects at the neuromuscular junction.