This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autacoids, Subject name: Pharmacology
[{'content': 'Histamine blocker in stomach act through \nSelect and explain. \nA. Decreasing cAMP in stomach, B. Increasing cAMP in stomach, C. Increasing IP3 in stomach, D. Decreasing IP3 in stomach', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Histamine H2 blockersinhibit the action of histamine ongastric H2 receptors thereby decreasing gastric acidity. They were considered a breakthrough in the treatment of peptic ulcer disease when first introduced. Refer kDT 6/e 153', 'role': 'assistant'}]