Which statement describes Angiotensin II's effect on norepinephrine release?

Which statement describes Angiotensin II's effect on norepinephrine release?

• A. No effect on NE release
• B. Decreases NE release
• C. Increases NE release
• D. Causes vasodilation independently of NE

Answer: (C)

Angiotensin II can amplify sympathetic signaling by acting on AT1 receptors on presynaptic sympathetic nerve terminals. When Ang II binds these sites, it increases intracellular calcium and promotes the exocytosis of norepinephrine, so more NE is released into the synaptic cleft. This boost in NE release enhances vasoconstriction and raises blood pressure, especially when the renin-angiotensin system is activated. So, the statement describing Ang II as increasing norepinephrine release best captures its effect. The other notions don’t fit as well: Ang II does not have no effect on NE release, nor does it decrease NE release. It also does not cause vasodilation independently of NE; its primary vascular action is vasoconstriction via AT1 receptor activation, which can be amplified by increased NE release rather than occurring as a separate, NE-independent vasodilatory effect.

Angiotensin II can amplify sympathetic signaling by acting on AT1 receptors on presynaptic sympathetic nerve terminals. When Ang II binds these sites, it increases intracellular calcium and promotes the exocytosis of norepinephrine, so more NE is released into the synaptic cleft. This boost in NE release enhances vasoconstriction and raises blood pressure, especially when the renin-angiotensin system is activated. So, the statement describing Ang II as increasing norepinephrine release best captures its effect.

The other notions don’t fit as well: Ang II does not have no effect on NE release, nor does it decrease NE release. It also does not cause vasodilation independently of NE; its primary vascular action is vasoconstriction via AT1 receptor activation, which can be amplified by increased NE release rather than occurring as a separate, NE-independent vasodilatory effect.