Thick Ascending Limb Flashcards
What are the three regions of the loop of Henlé?
- Thin descending limb
- Thin ascending limb
- Thick ascending limb
What occurs at the thin descending limb?
H2O leaves
What occurs in the thin ascending limb?
Na+ and Cl- leaves
What occurs in the thick ascending limb?
Na+ and Cl- leaves
What is the function of the loop of Henlé?
Control [urine]
What are apical membrane channels/transporters in the thick ascending limb?
NKCC2 and ROMK (KIR1.1)
What are basolateral membrane channels/transporters in the thick ascending limb?
CLCK
Which protein needs to be present for CLCK to be functional?
Barttin
What is Barttin?
The protein needed to be present for CLCK to work
What is CLCK?
Chloride ion channel for taking out Cl- on basolateral side
What is Bartter’s syndrome?
A recessive inheritance mutation which affect NKCC2. ROMK, CLCK and Barttin
What are the symptoms of Bartter’s syndrome?
- Salt washing
- Polyuria
- Hypotension
- Hypokalaemia
- Hypercalciuria
- Metabolic alkalosis
- Nerphrocalcinosis
What does the ROMK knockout mouse show?
Unable to recycle K+ across apical membrane
Acidosis in mutant mice
What is different between ROMK knockout mice and Bartter’s patients?
Mice show acidosis whereas humans display alkalosis
And plasma [K+] increases in mice but decreases in humans
Examples of loop diuretics
Furosemide and bumetanide
How do diuretics work?
Inhibit sodium reabsorption which inhibits H2O reabsorption so increase urine flow rate
What does the early distal tubule reabsorb?
Na+, Mg2+ and Cl-
What kind of diuretics are early distal tubule cells sensitive to?
Thiazide
Membrane channels on the apical side of the early distal tubule
- NCC
- Magnesion ion channel
What does NCC do?
Transport Na+ and Cl- into the cell on the apical side of the early distal tubule
Membrane channels on the basolateral side of the early distal tubule
- Potassium channel
- CLCK with Barttin
What is Gitelman’s syndrome? Symptoms
Recessive genetic disorder with similar symptoms to Bartter’s except HYPERcalciuria
Give an example of a thiazide diuretic
Chlorothiazide
What are the side effects of using thiazide diuretics?
Gitelman’s-like symptoms
What are the side effects of using loop diuretics?
Bartter’s-like symptoms
Heterozygotic mutations in what protects against hypternsion?
ROMK, NCC or NKCC2
What does NKCC2 transport?
K+, Na+ and 2Cl^- into the cell on the apical side
