In a hypovolemic patient, angiotensin II acts on the renal glomerular arterioles to preserve glomerular filtration rate. Which vascular effect best explains this protective mechanism?

• A Preferential constriction of the efferent arteriole ✓
• B Preferential constriction of the afferent arteriole
• C Equal constriction of afferent and efferent arterioles
• D Prostaglandin-mediated afferent arteriolar vasodilation

Explanation

Angiotensin II preferentially constricts the efferent arteriole, raising glomerular capillary hydrostatic pressure and maintaining GFR despite reduced renal plasma flow. This increases filtration fraction. Option C would not selectively sustain glomerular pressure. Option B would reduce glomerular pressure and worsen GFR. Option D describes a compensatory afferent dilatory mechanism (prostaglandins) seen in some hypovolemic states, but it is not the angiotensin II-mediated protective effect.

Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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