Final answer:
Beta-blockers are used to manage hypertension by blocking adrenaline's action on β-receptors, thus lowering heart rate and blood pressure. Side effects include bradycardia and orthostatic hypotension, while bronchoconstriction can occur in asthmatic patients. Erectile dysfunction is a side effect, but not priapism.
Step-by-step explanation:
β-adrenoceptor blockers, commonly referred to as β-blockers, are medications that are primarily used to manage hypertension and other cardiovascular conditions by inhibiting the action of adrenaline on β-receptors. These drugs, such as metoprolol and propranolol, bind to G-protein-linked receptors in heart muscles and prevent adrenaline from initiating a chain reaction that would typically lead to increased heart rate and vasoconstriction. Adrenaline generally exerts a stimulatory effect on both the heart rate and blood pressure, but β-blockers counteract this by promoting inhibitory effects, resulting in a decrease of these parameters.
Side effects of β-blockers can vary depending on their specificity to β1 or β2 receptors. In general, side effects may include bradycardia, orthostatic hypotension, and in cases of overprescription, heart stoppage. It is important to note that they can cause bronchoconstriction in asthmatic patients due to the blocking of β2 receptors, which normally mediate smooth muscle relaxation in the bronchi. Erectile dysfunction can also occur but priapism is not a recognized side effect. If considering their use for urinary issues, β-blockers might lead to urinary retention, though orthostatic hypotension is a more common side effect.
Given these uses and effects, the correct hypothesis regarding the mechanism of action for β-blockers would be that they exert an antagonistic effect to adrenaline, thus reducing heart rate and blood pressure by inhibiting the G-protein signaling pathways associated with vasoconstriction and cardioacceleration.