Final answer:
Selective cardioselective beta blockers like metoprolol and propranolol treat hypertension by blocking the beta-1 receptor in the heart, which slows the heart rate. Metoprolol is cardioselective while propranolol is nonselective, affecting other receptors as well. Overprescription can lead to serious side effects like bradycardia.
Step-by-step explanation:
The two drugs that are selective or cardioselective beta blockers to treat hypertension are metoprolol and propanolol. Metoprolol specifically blocks the beta-1 (β1) receptor, which is primarily located in the heart, leading to its designation as cardioselective. This drug can be effective in managing high blood pressure by slowing down the heart rate (HR), without significantly affecting beta-2 receptors that are found in the lungs and blood vessels. Propranolol, on the other hand, is a nonselective beta blocker that blocks both beta-1 and beta-2 receptors, therefore it affects not only the heart but also the lungs and vasculature.
Care must be taken with these medications as overprescription can lead to bradycardia (abnormally slow heart rate) or even cardiac arrest. Beta blockers improve cardiac function by inhibiting the effects of adrenaline and noradrenaline (NE) on the sympathetic nervous system, which typically would increase heart rate and cause vasoconstriction.