All of the following statements about neuromuscular blockage produced by succinylcholine are true, Except–
**Core Concept**
Succinylcholine is a depolarizing neuromuscular blocking agent that mimics the action of acetylcholine at the neuromuscular junction, causing muscle depolarization and subsequent flaccid paralysis.
**Why the Correct Answer is Right**
Succinylcholine's mechanism of action involves binding to nicotinic acetylcholine receptors on the muscle endplate, leading to a prolonged depolarization of the muscle cell membrane. This results in muscle contraction followed by prolonged flaccid paralysis. Succinylcholine is metabolized by plasma cholinesterase, a enzyme that rapidly breaks down the drug, contributing to its short duration of action.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because succinylcholine does not cause muscle fasciculations at the neuromuscular junction. Fasciculations are typically seen with non-depolarizing neuromuscular blockers.
* **Option B:** This option is incorrect because succinylcholine's effect is not reversed by anticholinesterases such as neostigmine. Anticholinesterases work by inhibiting the breakdown of acetylcholine, but succinylcholine's prolonged depolarization is due to its direct action on nicotinic receptors, not the depletion of acetylcholine.
* **Option C:** This option is incorrect because succinylcholine does not have a direct effect on the autonomic nervous system. While it can cause a transient increase in heart rate and blood pressure due to muscle contraction, its primary action is on the neuromuscular junction.
**Clinical Pearl / High-Yield Fact**
Succinylcholine is contraindicated in patients with muscular dystrophy, spinal cord injury, and burn patients due to the risk of hyperkalemia and cardiac arrhythmias. This is because these conditions can lead to an increased number of acetylcholine receptors on the muscle endplate, making the patient more sensitive to succinylcholine.
**Correct Answer: D.**