What physiological state do agonist (depolarizing) neuromuscular blockers induce?

Agonist (depolarizing) neuromuscular blockers induce a physiological state known as flaccid paralysis. These agents work by binding to nicotinic acetylcholine receptors at the neuromuscular junction, leading to an initial depolarization of the muscle fiber membrane. This initial phase causes muscle twitching, but continued exposure prevents further muscular contraction due to the sustained depolarization of the receptor sites. As a result, the muscle fibers cannot repolarize, which effectively means they cannot contract, leading to a state of flaccid paralysis.

This type of paralysis is characterized by the loss of tone and strength in the muscles, making it impossible for voluntary movements to occur. Flaccid paralysis extends to all skeletal muscles supplied by the affected motor nerves, which is particularly useful in certain surgical procedures requiring complete muscle relaxation. Understanding the mechanism of action of these blockers is crucial, as it highlights their role in facilitating surgery and managing conditions requiring rapid muscle relaxation.