This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hematology, Subject name: Pharmacology
[{'content': 'Mechanism of action of aspirin as antiplatelet drug is its inhibitory action on? \nSelect and explain. \nA. Prostacyclins, B. PGF 2 alpha, C. Thromboxane A2, D. Phospholipase C', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (C) Thromboxane A2(Ref: KDT 8/e p677)By inhibiting cyclooxygenase enzyme, aspirin initially decreases the level of both prostacyclins (in endothelium) and TXA2 (in platelets). However after some time prostacyclin synthesis resumes due to presence of nucleus in endothelium whereas TXA2 remain depressed because platelets are enucleated. Thus final effects of aspirin are due to decrease in TXA2 synthesis.', 'role': 'assistant'}]