This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'Which of the following best describes a pharmacologic propey of amiodarone? \nSelect and explain. \nA. a-Adrenergic agonist, B. b-Adrenergic agonist, C. Activation of Ca 2+ channels, D. Inhibition of K + channels', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Amiodarone Mech of action:- It is iodine containing highly lipophilic long-acting antiarrhythmic drug exes multiple actions: * Prolongs APD and Q-T interval attributable to block of myocardial delayed rectifier K+ channels. This also appears to reduce non-uniformity of refractoriness among different fibres. * Preferentially blocks inactivated Na+ channels (like lidocaine) with relatively rapid rate of channel recovery: more effective in depressing conduction in cells that are paially depolarized or have longer APD. * Paially inhibits myocardial Ca2+ channels, has noncompetitive b adrenergic blocking propey and alters thyroid function. Ref:- kd tripathi; pg num:-533', 'role': 'assistant'}]