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
Dales vasomotor re-reversal is due to 
Select and explain. 
A. Stimulation of alpha-1 receptors, B. Stimulation of beta-2 receptors, C. Blockade of beta -2 receptors, D. Blockade of alpha-1 receptors
A: Stimulation of alpha-1 receptors
Answer: A: Stimulation of alpha-1 receptors 
Explanation: 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.