This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pancreas, Subject name: Pharmacology
Which of the following patients is most likely to be treated with intravenous glucagon? 
Select and explain. 
A. A young man who took cocaine and has a blood pressure of 190/110 mm Hg, B. A middle aged man with type II diabetes who has not taken his regular dose of glipizide for last 4 days, C. An old man with severe bradycardia and hypotension resulting from ingestion of overdose of atenolol, D. An old woman with lactic acidosis as a complication of severe infection and shock
C: An old man with severe bradycardia and hypotension resulting from ingestion of overdose of atenolol
Answer: C: An old man with severe bradycardia and hypotension resulting from ingestion of overdose of atenolol 
Explanation: Glucagon : Use in hypoglycemia DOC for beta blocker poisoning A life-threatening adverse cardiac effect of a b antagonist may be overcome directly with isoproterenol or with glucagon (glucagon stimulates the hea glucagon receptors, which are not blocked by b antagonists), but neither of these methods is without hazard.