What is the mechanism of action of α1 antagonists?

The mechanism of action of α1 antagonists is to block alpha-1 adrenergic receptors, which are primarily found on vascular smooth muscle. When these receptors are activated by norepinephrine and epinephrine, they cause vasoconstriction, leading to an increase in blood pressure. By antagonizing these receptors, α1 antagonists lead to vasodilation, which decreases vascular resistance and lowers blood pressure. This effect makes them useful in the treatment of hypertension and can also provide relief from urinary symptoms in benign prostatic hyperplasia.

The other options do not accurately describe the primary mechanism of α1 antagonists. For instance, blocking calcium channels is a mechanism associated with different classes of drugs, such as calcium channel blockers, which primarily affect the contraction of the heart and vascular smooth muscle by preventing calcium ions from entering the cells. Reducing heart rate is more characteristic of β-blockers, which act on β-adrenergic receptors in the heart. Increasing renin production is not related to the action of α1 antagonists; in fact, blocking α1 receptors can lead to a compensatory increase in renin release as part of the body’s regulatory processes. Thus, α1 antagonists directly induce vasodilation through beta-adr