3. Physiology
        3.12. Renal
            3.12.6. Renal handling of sodium, chloride and water
3.12.6.4. Sodium reabsorption

Sodium reabsorption

Transporters involved in sodium reabsorption

Apical membrane of tubular cells

Proximal tubules

Symporters
Antiporters
Channels

Basolateral membrane of tubular cells

Proximal tubule

Na-K ATPase pump in basolateral membrane powers all of the actions

Na-H antiporter

Accounts for

Others

Loop of Henle

Descending limb

Effect of descending limb

Ascending limb - thin

Passive reabsorption of Na+

NB:

Ascending limb - thick

Active reabsorption of Na+

Other routes of Na+ reabsorption
Na-K-2Cl symporter
Paracellular route

Due to

NB:

Effect of ascending limb

Overall effect of LOH

--> More solute is reabsorbed than water

--> Dilution of filtrate

Thus,

Distal convoluted tubule

Na-Cl symporter

Collecting ducts

Sodium reabsorption
* via apical Na+ channel (i.e. ENaC) in principle cells
* Not affect much by ADH level

Medullary collecting ducts

Some Na reabsorption

???? Via ENaC

 



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