Diuretics

Question 0

Drug that works in the Loop of Henle?

Answer 0

Frusemide.

Blocks Na+/Cl- co transport

Question 1

What are the important areas of sodium reabsorption in nephrons?

Answer 1

Ascending limb of the loop of henle
Early part of distal tubule
Late part of distal tubule
(Sites of diuretic action)

Question 2

Drugs that work in the proximal part of the proximal convoluted tubule?

Answer 2

Thiazides and indapamide

Blocks Na+/Cl- co transport

Question 3

What is spironolactone?

Answer 3

Aldosterone antagonist.

Compete for aldosterone intracellularly receptor hence inhibits distal Na+ retention and K+ secretion.

Question 4

What is amiloride?

Answer 4

Na+ channel blocker that works in the distal part of the distal convoluted tubule.
Inhibits Na+ reabsorption by blocking lumenal sodium channels and decreasing K+ excretion.

Question 5

Why is H2O reabsorption passive?

Answer 5

It depends on the osmotic gradient between the tubule lumen and the interstitium. The osmotic gradient depends on the Na+ concentration gradient and the transfer of Na+. Preventing Na+ reabsorption reduces the osmotic gradient. Less H2o is reabsorbed and more is excreted.

Question 6

What are the clinical uses of diuretics?

Answer 6

Hypertension - lower blood volume

Heart failure - excrete retained Na+ and H2O

Question 7

What are diuretics?

Answer 7

They increase the excretion of Na+ and water. They do this by decreasing the reabsorption of Na+ and usually Cl- from the filtrate.