Kidney function question

[nokia8650]

i was struggling with the following question:

Partial occlusion of one renal artery is likely to result in which ONE of the following:
A. Increased renin secretion from both kidneys
B. Increased sodium excretion
C. Constriction of the efferent arteriole of the other kidney
D. Dilatation of the efferent arteriole of the other kidney
E. A gradual reduction in arterial blood pressure over time

Please could someone explain the answer?

Thank you very much.

 

[adrenaline]

I'm pretty sure it is C. The reduced pressure in the afferent arteriole in the kidney stimulates renin release by the affected kidney, which increases circulating angiotensin II and aldosterone. I'm pretty sure the efferent arteriole constriction is mediated by angiotensin II so both efferents will be constricted.