Amlodipine is a calcium channel blocker. In high blood pressure, it normalizes the blood pressure by relaxing the blood vessels to reduce the pressure on them, thereby improving the blood flow in the body. The enhanced blood flow in the body, further relaxes the heart muscles by reducing the workload on the heart. It also improves the oxygen flow in the body, thereby, preventing any heart-related chest pain. Atenolol is a type of medicine called a beta blocker. Like other beta blockers, atenolol works by changing the way your body responds to some nerve impulses, including in the heart. It slows down your heart rate and makes it easier for your heart to pump blood around your body.