This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
[{'content': 'Treatment of hypeensive crisis in pheochromocytoma \nSelect and explain. \nA. Phentolamine, B. Hydralazine, C. Guanethidine, D. Salameterol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref:KD Tripathi 7thE pg: 565 Phentolamine is used for pheochromocytoma. Note Non selective alfa-blockers cause fall in t.p.r, which is compensated by increased HR and C.O. So, they are not used routinely for htn. They block both alfa-1 and alfa-2 receptors- NA release is accentuated. Reserved for special situations like pheochromocytoma, clonidine withdrawal, cheese reaction, where circulating CA&;s are responsible for the rise in BP.', 'role': 'assistant'}]