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 drugs will decrease hea rate in a patient with a normal hea rate but will have little effect on hea rate in a cardiac transplant recipient \nSelect and explain. \nA. Adrenaline, B. Noradrenaline, C. Isoproterenol, D. Phenylephrine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref-KDT 6/e p127 Nor-adrenaline decreases the hea rate due to reflex stimulaton of baroreteptors. These reflexes are lost in a transplanted hea. however, by its acton, it can produe tachycardia phenylephiine is a selective alpha1 agonist. It has no direct eftect on the hea but produes bradyardi due to reflex stimulation o baro-receptors. These retlexes are lost in a translanted hea. Therelore, it produces no etfect on hea.', 'role': 'assistant'}]