This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
[{'content': 'Dales vasomotor re-reversal is due to \nSelect and explain. \nA. Stimulation of alpha-1 receptors, B. Stimulation of beta-2 receptors, C. Blockade of beta -2 receptors, D. Blockade of alpha-1 receptors', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Reversal phenomenon - seen by giving alpha blocker-blockade of alpha 1 receptors - only fall in BP is seen due to stimulation of beta 2 receptors. Re reversal- IV Adrenalin administration - then beta-blocker administration - then adrenaline again - only rise in BP due to stimulation of alpha 1 receptors. Ref: Goodman Gillman 11th ed. Pg. 330.', 'role': 'assistant'}]