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': 'Oaubain acts by inhibiting \nSelect and explain. \nA. Adenyl cyclase, B. Ca+ chanells, C. H+K+ ATPase, D. Na+K+ATPase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ouabain is a cardiac glycoside and in lower doses, can be used medically to treat hypotension and some arrhythmias. It acts by inhibiting the Na/K-ATPase, also known as the sodium-potassium ion pump Refer kDT 6/e p496', 'role': 'assistant'}]