This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: A.N.S., Subject name: Pharmacology
[{'content': 'Reflex tachycardia is most likely to occur after the systemic administration of \nSelect and explain. \nA. albuterol, B. methoxamine, C. phenylephrine, D. propranolol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Although used primarily via inhalation for asthma, systemic effects of albuterol include vasodilation due to its b2 receptor activation. This can result in a decrease in PVR and mean BP, which elicits a reflex tachycardia. Methoxamine and phenylephrine are a- receptor activators causing vasoconstriction, which would result in reflex bradycardia. Ganglion blockers (trimethaphan) prevent autonomic reflexes, and a reflex increase in heart rate could not occur in the presence of a beta blocker (propranolol).', 'role': 'assistant'}]