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': 'Mechanism of action of sodium nitrate in cyanide poisoning is \nSelect and explain. \nA. Produces methamoglobinemia, B. Increased blood flow to liver, C. Increased blood flow to hea, D. Increased blood flow to kidney', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Sodium nitroprusside contain 1 Iron molecule coordinated to five cyanide molecules and one molecule of nitric oxide Prolonged use of Sodium nitroprusside may cause cyanide poisoning Detoxification occurs when cyanide and methamoglobin combines to form cyanomethamoglobin. Amyl nitrate and sodium nitrates enhance the oxidation of hemoglobin to methamoglobin, ensuring reliable mechanism of detoxification Refer kDT 6/e p 527', 'role': 'assistant'}]