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
[{'content': 'Digitalis has positive inotropic effect-by the virtue of its effect on: \nSelect and explain. \nA. Na+ K+ ATPase pump, B. Na Glucose channels, C. H+K+ ATPase pump, D. Calcium Pump', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Digitalis binds selectively to Na+\xa0K+ATPase and inhibits this pump. \nThus it increases intracellular Na+\xa0and decreases extrusion of Ca2+', 'role': 'assistant'}]