What is one of the main actions of ANP?

Atrial Natriuretic Peptide (ANP) primarily functions to regulate blood pressure and fluid balance in the body. One of its main actions is the dilation of peripheral blood vessels. This vasodilatory effect helps to decrease systemic vascular resistance, leading to a drop in blood pressure.

Additionally, ANP promotes natriuresis, which is the excretion of sodium through the urine, thereby contributing to a reduction in blood volume. This is a critical mechanism to counteract the effects of excessive fluid retention often regulated by hormones such as aldosterone. By causing vasodilation and promoting natriuresis, ANP plays a significant role in maintaining cardiovascular homeostasis and preventing conditions such as hypertension.

In contrast, promoting peripheral vessel contraction goes against the primary action of ANP, as it facilitates vasodilation instead. Inhibiting renal Na+ excretion would also contradict its function, as ANP actually encourages the excretion of sodium. Lastly, stimulation of thirst is primarily the role of other hormones such as angiotensin II, rather than ANP, which acts to decrease fluid volume and pressure. Therefore, the correct answer reflects ANP's role in vasodilation, which is vital for its physiological effects on blood pressure regulation