Role of Aquaporins in Renal Water Transport

Question 1

What is the name of the aquaporin channel responsible for transcellular movement in the proximal tubule and the thin descending Loop of Henle?

Answer 1

AQP1

Question 2

What are the 3 aquaporin channels located in the principle cells of the collecting ducts?

Answer 2

AQP2, AQP3, AQP4

Question 3

Which aquaporin channel responds to AVP in the collecting duct?

Answer 3

AQP2

Question 4

On which side of the membrane of the priniciple cells are AQP3 and AQP4 located on? Apical or basolateral?

Answer 4

Basolateral

Question 5

Through what intracellular second messenger does AVP work through in the principle cells?

Answer 5

cAMP

Question 6

What does cAMP do when activated by AVP during SHORT-term water regulation?

Answer 6

Activates dormant vesicles containing AQP2 channels to fuse with the apical membrane and allow for water transport.

Question 7

How does AVP increase water permeability during LONG-term water regulation?

Answer 7

Enhances long-term transcription of the AQP2 gene. Transcription of this gene creates more AQP2 aquaporin channels that can be inserted into the apical membrane.

Question 8

What compound degrades AVP, usually seen during the 3rd trimester of pregnancy?

Answer 8

Vasopressinase

Question 9

What are the characteristics of vasopressinase?

Answer 9

A placental aminopeptidase

Question 10

Someone with elevated levels of vasopressinase may look like they have?

Answer 10

Central DI

Question 11

If you have increased (relative to normal) expression of the AQP2 gene, what do you expect to observe clinically?

Answer 11

Abnormal amount of fluid retention