Acetylcholine then diffuses across the synaptic cleft.
It may be hydrolysed by acetylcholine esterase (Ach E) or bind to the nicotinic receptors located on the motor end plate.
It reduces skeletal muscle strength by inhibiting the excitation-contraction coupling in the muscle fiber.
In normal muscle contraction, calcium is released from the sarcoplasmic reticulum through the ryanodine receptor channel, which causes the tension-generating interaction of actin and myosin.
Its active ingredient, tubocurarine, as well as many synthetic derivatives, played a significant role in scientific experiments to determine the function of acetylcholine in neuromuscular transmission.
Other skeletal muscle relaxants of that type used around the world come from a number of drug categories and other drugs used primarily for this indication include orphenadrine (anticholinergic), chlorzoxazone, tizanidine (clonidine relative), diazepam, tetrazepam and other benzodiazepines, mephenoxalone, methocarbamol, dantrolene, baclofen, Drugs once but no longer or very rarely used to relax skeletal muscles include meprobamate, barbiturates, methaqualone, glutethimide and the like; some subcategories of opioids have muscle relaxant properties, and some are marketed in combination drugs with skeletal and/or smooth muscle relaxants such as whole opium products, some ketobemidone, piritramide and fentanyl preparations and Equagesic.
Muscle relaxation and paralysis can theoretically occur by interrupting function at several sites, including the central nervous system, myelinated somatic nerves, unmyelinated motor nerve terminals, nicotinic acetylcholine receptors, the motor end plate, and the muscle membrane or contractile apparatus.
Spasmolytic agents generally work by either enhancing the level of inhibition, or reducing the level of excitation.
Inhibition is enhanced by mimicking or enhancing the actions of endogenous inhibitory substances, such as GABA.
Most neuromuscular blockers function by blocking transmission at the end plate of the neuromuscular junction.