How does Prazosin primarily affect blood vessels?

Prazosin primarily affects blood vessels by dilating peripheral blood vessels. It is classified as an alpha-1 adrenergic antagonist, which means it blocks the action of norepinephrine on alpha-1 receptors located on vascular smooth muscle. When these receptors are inhibited, the smooth muscle relaxes, leading to vasodilation. This action reduces vascular resistance, which in turn lowers blood pressure.

The mechanism of vasodilation is particularly important in the management of conditions like hypertension and benign prostatic hyperplasia, where reducing vascular tone helps alleviate symptoms and decreases the workload on the heart. Due to its relaxant effect on blood vessels, Prazosin is effective at improving blood flow and can help enhance oxygen delivery to tissues.

The other choices do not accurately represent Prazosin's mechanism of action. It does not work by constricting blood vessels, blocking calcium influx, or stimulating beta receptors, as those actions would lead to increased blood pressure rather than the desired vasodilatory effect.