This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'All of the following drugs act by blocking calcium channel except \nSelect and explain. \nA. Dantrolene, B. Nicardipine, C. Diltiazem, D. Verapamil', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Refer kDT 6/e p 529 Dantrolene sodium is a postsynaptic muscle relaxant that lessens excitation-contraction coupling in muscle cells. It achieves this by inhibiting Ca2+ ions release from sarcoplasmic reticulum stores by antagonizing ryanodine receptors. It is the primary drug used for the treatment and prevention of malignant hypehermia, a rare, life-threatening disorder triggered by general anesthesia. It is also used in the management of neuroleptic malignant syndrome, muscle spasticity (e.g. after strokes, in paraplegia, cerebral palsy, or patients with multiple sclerosis), and 2,4-dinitrophenol poisoning, and the related compounds dinoseb and dinoterb.', 'role': 'assistant'}]