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Certain statements are put forth on the regulation of renal blood flow and are given below:

A. Norepinephrine dilates the renal vessels.
B. Dopamine causes renal vasodilation and natriuresis.
C. Angiotensin II exerts a constrictor effect.
D. Prostaglandins decrease blood flow in the renal cortex and increase it in the medulla.
E. Acetylcholine produces renal vasodilation.

Choose the option with the combination of all correct statements.

Correct option is C

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Explanation:

1. Statement A - Incorrect
• Norepinephrine primarily causes vasoconstriction of renal blood vessels by activating α1-adrenergic receptors, leading to a decrease in renal blood flow.
2. Statement B - Correct
• Dopamine induces renal vasodilation and promotes natriuresis (sodium excretion) by acting on D1 receptors in renal vasculature, improving renal perfusion.
3. Statement C - Correct
• Angiotensin II is a potent vasoconstrictor, primarily affecting the efferent arteriole, helping to maintain glomerular filtration rate (GFR) despite reduced renal blood flow.
4. Statement D - Incorrect
• Prostaglandins (PGE2 and PGI2) usually promote renal vasodilation, counteracting the vasoconstrictive effects of norepinephrine and angiotensin II. They do not significantly decrease blood flow in the renal cortex.
5. Statement E - Correct
• Acetylcholine (ACh) promotes renal vasodilation by stimulating muscarinic M3 receptors, leading to the release of nitric oxide (NO), which increases renal perfusion.