Renal System

Question 1

Transport in cells of proximal tubule

Answer 1

Apical: SGLT1 and SGLT2 (glucose and Na+ into cell), NapiII (PO42- and glucose into cell) NHE3 (H+ out, Na+ in)

Question 2

Transport in cells of thick ascending limb (loop of Henle)

Answer 2

Apical: ROMK (recycling of K+ into lumen), NKCC2 (Na+, K+ and 2Cl- into cell)

Basolateral: CLCK + Barttin (Cl- out of cell into interstitial fluid)

Question 3

Transport in cells of early distal tubule

Answer 3

Apical: NCC (Na+ and Cl- into cell)
Basolateral: CLCK (Cl- out of cell into interstitial fluid)
Both: Mg2+ channel (Mg2+ movement into and out of cell into interstitial fluid)

Question 4

Transport in cells in principal cells of late distal tubule

Answer 4

Apical: ROMK (K+ into lumen) ENaC (Na+ into cell), AQP2 (H2O into cell)

Basolateral: APQ3/APQ4 (H2O into interstitial fluid), Kir2.3 (K+ into interstitial fluid)

Question 5

Transport in cells of ⍺ intercalated cells of late distal tubule

Answer 5

Apical: H+ATPase (active transport of H+ into lumen)

Basolateral: AE1 (Cl- into cell, HCO3- into interstitial fluid) Cl- channel (recycling of Cl- into the interstitial fluid)

Question 6

Transport in cells of β intercalated cells of late distal tubule

Answer 6

Apical: AE1 (Cl- into cell, HCO3- into interstitial fluid)

Basolateral: H+ATPase (H+ into interstitial fluid), Cl- channel (CL- into interstitial fluid)

Question 7

What channels are mutated in Barrter’s patients?

Answer 7

NKCC2 – loss of ability to reabsorb sodium and chloride
CLCK – Chloride accumulates in cell, stops NKCC2 transporting
Barttin – CLCK channels stop working
ROMK – stops recycling of K+, not enough K+ to support function of NKCC2

Question 8

Symptoms of Bartter’s syndrome

Answer 8

Polyuria
Hypotension
Hypokalaemia
Metabolic alkalosis
Hypercalciuria
Nephrocalcinosis

Question 9

Symptoms of gitelman’s syndrome

Answer 9

Polyuria
Hypotension
Hypokalaemia
Metabolic alkalosis
Hypocalciuria

Question 10

What channel is mutated in Gitelman’s syndrome?

Answer 10

Loss of function mutation in NCC - No reabsorption of NA+ and Cl-

Question 11

Loop Diuretics

Answer 11

Loop of Henle - Thick Ascending Limb

Blocks NCC

Chlorothiazide

Question 12

Thiazide Diuretics

Answer 12

Targets Early Distal Tubule

Blocks NCC

Chlorothiazide

Question 13

K+ Sparing Diuretics

Answer 13

Late Distal Tubule – Principal Cells

Blocks ENaC

Amiloride