This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hypeension, Arrhythmias, Dyslipidemia, Subject name: Pharmacology
[{'content': 'A drug effect that is produced by therapeutic doses of both timolol and amiodarone is blockade of: \nSelect and explain. \nA. Cardiac Na+ channels, B. Cardiac K+ channels, C. Beta adrenoceptors, D. Alpha-adrenoceptors', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Amiodarone has wide spectrum of antiarrhythmic actions. It acts by all the four mechanisms: blockade of Na+ channels blockade of b receptors blockade of K+ channels blockade of Ca2+channels. Timolol is a b blocker. Therefore, common action of these two drugs is inhibition of b-receptors.', 'role': 'assistant'}]