4. Reabsorption Of Sodium Along The Tubule

Question 1

What are the transporters in the PCT?

Answer 1

Basolateral - 3Na-2K-ATPase
Apical - Na/H exchange, co-transport with glucose, co-transport with AA or carboxylic acids, co-transport with phosphate , Na+/2Cl-/K+ transporter, ROMK
Aquaporin 1

Question 2

What is amiloride?

Answer 2

Diuretic that inhibits ENaC in DCT

Blocks Na+/H+ anti porter in PCT

Question 3

How are chloride ions reabsorbed?

Answer 3

Cl-/base- exchanger
Diffusion through tight junctions
Cl- channels on basolateral membrane

Question 4

What are loop diuretics and give an example

Answer 4

Block NA+/2Cl-/K+ transporters

E.g. furosemide

Question 5

What happens in the DCT?

Answer 5

Water permeability fairly low
Active Na+ reabsorption - stimulated by aldosterone
Water permeability is variable depending on ADH

Question 6

What are ENaC?

Answer 6

Epithelium sodium channels

Allow passive movement of Na+

Question 7

What do thiazides diuretics work?

Answer 7

Block Na+/Cl- transporters

Question 8

What does amiloride do?

Answer 8

Block Na+ channels

Question 9

What is the collecting duct divided up into?

Answer 9

Cortical (CCD)

Medullary (MCD)

Question 10

What are the 2 cell types in the CD?

Answer 10

Principal cells and intercalated cells

Question 11

What do potassium sparing diuretics do?

Answer 11

Either block aldosterone receptor antagonists or block ENaC channels