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
Cardiac conduction defect seen with Tricyclic antidepressants are due to- 
Select and explain. 
A. NE & serotonin uptake inhibitor, B. Antimuscarinic action on hea, C. Only NE uptake inhibition, D. Both NE uptake inhibition and antimuscarinic action on hea
D: Both NE uptake inhibition and antimuscarinic action on hea
Answer: D: Both NE uptake inhibition and antimuscarinic action on hea 
Explanation: Ans. is 'd' i.e., Both NE uptake inhibition and antimuscarinic action on hea o The commonest cardiovascular effect of tricyclic antidepressant overdose is sinus tachycardia, which is attributable to the inhibition of norepinephrine reuptake and the anticholinergic action.