Distal Tubule and Collecting Duct Genes Flashcards
(26 cards)
What are the 2 cell types of the distal tubule?
- Principal
- Intercalated
What are the two types of collecting duct cell types?
Principal and intercalated
What are the two types of intercalated cell?
α and ß
α is acid-releasing and more present in Western, high-protein, diets
What membrane channels are found on the basolateral side of a principal cell of the collecting?
Kir 2.3
AQP3
AQP4
What membrane channels are found on the apical side of a principal cell of the collecting?
ENaC
ROMK
Aquaporin 2
What does Kir2.3 transport?
K+ out on the basolateral side of a principal cell
What does AQP3 and AQP4 transport?
H2O out on the basolateral side of a principal cell
Give some examples of diseases of the principal cell of the collecting duct
Diabetes insipidus - AQP2
Liddle’s syndrome - ENaC
Pseudohypoaldosteronism
Give an example of a potassium-sparing diuretic
Amiloride
What does amiloride do?
Blocks ENaC inhibiting Na+ uptake at late distal tubule which reduces K+ secretion
What is secreted and reabsorbed in α intercalated cells of the collecting duct?
H+ secretion and HCO3^- reabsoprtion
Membrane proteins/channels of α intercalated cell
Apical
- H+ out using ATP
Basolateral
- AE1 - Cl^- in and HCO3^- out
- Chloride ion channel - Cl^- out
What is AE1?
An anion-exchanger
Transports HCO3^- out and Cl^- in
What do mutations in AE1 cause?
Distal renal tubular acidosis
- genetic inheritance
- nephrocalcinosis
- metabolic acidosis
- nephrolithiasis
What occurs when a gain-of-function mutation in AE1 occurs in an α intercalated cell?
It forms AE1 on the apical side too –> acidosis
Membrane proteins/channels of ß intercalated cell
Apical
- AE - HCO3^- out and Cl^- in
Basolateral
- H+ out using ATP
- Chloride ion channel - Cl^- out
Permeabilities of medullary collecting duct
- Low Na+ permeability
- High H2O and urea permeability in the presence of vasopressin
Where is H+ secreted and reabsorbed?
Secretion: Proximal tubule, principal cell and α intercalated cell
Reabsorption: ß intercalated cell
Where is HCO3^- secreted and reabsorbed?
Secretion: ß intercalated cell
Reabsorption: proximal tubule, principal cell and α intercalated cell
Where does aldosterone act?
Principal cells in collecting duct system
What do principal cell types reabsorb and secrete?
Na+ and H2O reabsorption
K+ and H+ secretion
What do intercalated cell types reabsorb and secrete?
H+ secretion/reabsorption
HCO3^- reabsorption/secretion
What types of intercalated cells are there? What does their ratio depend on?
α and ß
Depends on the acid-base state of the body
What membrane channels are found on the apical side of a principal cell of distal tubule?
- ENaC
- ROMK
- Aquaporin 2
