This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
[{'content': 'All of the following are actions of muscarinic antagonists except \nSelect and explain. \nA. Decreases gastric secretion, B. prolongs AV conduction, C. Decreases tracheobronchial secretions, D. Causes contraction of radial muscle of iris', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref:KD Tripathi pharmacology 7th edition (page.no: 114,115) Actions of Muscuranic antagonists (atropine) are CNS stimulation CVS: the prominent effect is tachycardia by decreasing the refractory period of the AV node and facilitate AV conduction. Gland; decrease sweat, salivary, tracheobronchial and lacrimatory secretion Smooth muscle: decrease tone and contraction Eye ; mydriasis by contraction of the radial muscle of iris Rise in body temperature', 'role': 'assistant'}]