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': 'Sildenafil acts by inhibiting? \nSelect and explain. \nA. PDE 2, B. PDE 5, C. Adenyl cyclase, D. Gaunyl cyclase', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sidenafil, verdenafil, tadalafil acts by inhibiting PDE5 they increase NO- increases blood supply to the penis making it erect But they can produce ceain cardiac events They are also used in Pul HTN Ref: KD tripathi 8th ed', 'role': 'assistant'}]