This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
[{'content': 'Mechanism of action of sodium nitrite in cyanide poisoning: \nSelect and explain. \nA. Produces methemoglobinemia, B. Increased blood flow to liver, C. Increased blood flow to heart, D. Increased blood flow to kidney', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (A) Produces methemoglobinemia(Ref: KDT 8th/e p591)*Sodium nitroprusside contains one iron molecule coordinated to five cyanide molecules and one molecule of nitric oxide. Prolonged use of sodium nitroprusside may result in cyanide poisoning.*Detoxification occurs when cyanide and methemoglobin combine to form cyanomethemoglobin. Amyl nitrite or sodium nitrite enhance the oxidation of hemoglobin to methemoglobin, ensuring a reliable mechanism of detoxification.', 'role': 'assistant'}]