This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
[{'content': 'Which of the following drug shows the phenomenon of vasomotor reversal of Dale after administration of an Alpha adrenergic blocker \nSelect and explain. \nA. Adrenaline, B. Nor-adrenaline, C. Isoprenaline, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref-KDT 6/e p123 vasomotor reversal ot dale is seen with adrenaline. When this drug is infused quickly, initially there is rise in blood pressure (due to sitmulation of a receptors) followed by prolonged fall (beta2 action). alpha-blocking drugs inhibit the initial rise and only fall in blood pressure is recorded. This is known as vasomotor reversal. Nor-adrenaline has no beta2 activity and isoprenaline lacks a activity, therefore cannot demonstrate this phenomenon.', 'role': 'assistant'}]