Diuretics

Question 1

Proximal Convoluted Tubule

Answer 1

Acetazolamide on NHE3
- inhibits Na+/HCO3- reabsorption
- inhibits carbonic anhydrase -> prevents HCO3- reabsorption -> HCO3- excreted
- treats glaucoma, altitude sickness, oedema, seizures, metabolic alkalosis

Question 2

TALH

Answer 2

Furosemide on NKCC2
- inhibits NKCC2 -> reduced Na+, K+, Cl- reabsorption -> osmotic diuresis
- side effects: ototoxicity, disrupts tubuloglomerular feedback
- treats oedema, hypertension, acute kidney injury, chronic kidney disease, pulmonary hypertension (NKCC1), corrects hyponateuremia

Question 3

Distal convoluted tubule

Answer 3

Thiazides on NCC
- inhibits Na+/Cl- symporter -> decreased Na+ reabsorption, increased Na+ in urine -> increased urine vol.
- increased K+ and Mg2+ excretion
- increased Ca2+ reabsorption
- treats hypertension, vasodilator

Question 4

Cortical collecting tubule (aldosterone antagonists)

Answer 4

Spironolactone and Eplerenone on ENaC
- competitive aldosterone antagonist
- downregulates ENaC expression -> increased Na+ secretion
- K+ retention
- side effects: hyperkalaemia, gynecomastia, menstrual irregularities, testicular atrophy, erectile dysfunction

Question 5

Cortical collecting tubule (block receptors)

Answer 5

Amiloride and Triamterene on ENaC
- blocks ENaC -> reduces Na+ reabsorption -> K+ and Mg2+ sparing
- side effects: hyperkalaemia -> vomiting, cramps, weakness, cardiac arrhythmias