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': 'All of the following drugs reduce afterload, except: \nSelect and explain. \nA. Enalapril, B. Propranolol, C. Hydralazine, D. Sodium nitroprusside', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref:KDT 6/e p504 Afterloadis reduced by the drugs having aerioler dilating propey. Propanolol is a non-selective beta-blocker. It can cause vasoconstriction by antagonizing beta2 mediated vasodilation. It, therefore do not decrease afterload.', 'role': 'assistant'}]