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
Cardiotoxicity of bupivacaine - 
Select and explain. 
A. Depressed pacemaker activity, B. Toxic compound damaging myocardial cells, C. Depressed neural control on hea, D. Vascular thrombosis and Myocardial ischemia
A: Depressed pacemaker activity
Answer: A: Depressed pacemaker activity 
Explanation: Ans. is 'a' i.e., Depressed pacemaker activity o Local anaesthetics block cardiac sodium channels and thus depress abnormal cardiac pacemaker activity, excitability, and conduction. At extremely high concentrations, local anaesthetics can also block calcium channels.