This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: JIPMER 2018, Subject name: Pharmacology
All adverse effects of theophylline are mediated by adenosine A1, receptor antagonism except: 
Select and explain. 
A. Cardiac arrhythmias, B. Diuresis, C. Seizures, D. GI discomfo
D: GI discomfo
Answer: D: GI discomfo 
Explanation: Theophylline cause bronchodilation 2 mechanism:(1) PDE inhibition(2) Adenosine A1 antagonism Adverse effect of Theophylline Mechanism Nausea and vomiting PDE inhibition Headache PDE inhibition Gastric discomfo PDE inhibition Diuresis Adenosine A1 antagonism Arrythmias PDE inhibition, Adenosine A1 antagonism Seizures Adenosine A1 antagonism