Dantrolene acts on -

Ans. is 'a' i.e., Raynodine receptor Dantroleneo Dantrolene is a directly acting skeletal muscle relaxant,o Mechanism of actionNormally excitation (depolarization of end plate) is coupled with contraction by Ca+2 - Excitation contraction coupling.Dantrolone acts on Ryanodine receptors (RyR) Calcium channels in sarcoplasmic reticulum of skeletal muscles and prevents their depolarization triggered opening - no release of intracellular Ca+2 - No excitation contraction coupling - No contraction.That means muscle contraction is uncoupled from depolarization of the membrane.o Dantrolene is DOC for malignant hyperthermia.It can also be used inNeuroleptic malignant syndrome.To reduce spasticity in UMN disorders, hemiplegia, paraplegia, cerebral palsy and multiple sclerosis.Muscular weakness is the dose limiting side effect.Other side effects are sedation, malaise, light headedness, troublesome diarrhoea and liver toxicity.Remembero Quinine also acts as directly acting muscle relaxant.o It increases refractory period and decreases excitability of motor end plates,o It can be used in nocturnal leg cramp.