This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': 'Earliest event in ischemic cardiac myocytes is: \nSelect and explain. \nA. Microvascular injury, B. Irreversible cell injury, C. Loss of contractility, D. ATP reduction to 50% normal.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Loss of contractility Features Time Onset of A TP depletion Seconds Loss of contractility <2 min A TP reduced to 50% of normal to 10% of normal 10 min 40 min Irreversible cell injury 20-40 min Microvascular injury > 1 hour', 'role': 'assistant'}]