This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Theophylline has an antagonistic interaction with which of the following receptor? 
Select and explain. 
A. Adenosine receptors, B. Bradykinin receptors, C. Histamine receptors, D. Imidazoline receptors
A: Adenosine receptors
Answer: A: Adenosine receptors 
Explanation: Theophylline has an antagonistic interaction with adenosine receptors. Adenosine acts as a local mediator in CNS, CVS and other organs, cause contraction of smooth muscles especially bronchial, dilates cerebral blood vessels, depress cardiac pacemaker and inhibits gastric secretion. Methylxanthines acts by antagonizing adenosine receptors resulting in opposite effects. Ref: Essentials of Medical Pharmacology, 5th Edition, Page 203