This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
[{'content': 'Nitrates act by - \nSelect and explain. \nA. Activate guanyl cyclase and decrease cGMP, B. Activate guanyl cyclase and increase cGMP, C. Activate adenyl cyclase and decrease cAMP, D. Activate adenyl cyclase and decrease cAMP', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Activate/Guanyl/cyclase and increase cGMP Mechanism of action of nitrates:* Organic nitrates are rapidly denitrated enzymatically in the smooth muscle cell to release nitric oxide (NO) which activates cytosolic guanyl cyclase - | cGMP - Vasodilatation.* Veins express greater amount of the enzyme that generates NO from organic nitrates than arteries - Account for the predominant venodilatory effect.", 'role': 'assistant'}]