Diuretics: Ch.2-4: Potassium sparing drugs

Question 1

What is a principal cell?

Answer 1

the site of Na/K/H2O transport in the collecting duct

Question 2

About how much NaCl is reabsorbed in the collecting duct?

Answer 2

5-10%

Question 3

What is the function of the alpha-intercalated cell of the collecting duct?

Answer 3

it’s the major site of H+ secretion

Question 4

What channel is responsible for Na+ reabsorption in the collecting duct?

Answer 4

ENaC (epithelial Na+ channels)

Question 5

This is a K+-sparing diuretic that is a competitive aldosterone receptor antagonist in the collecting duct.

Answer 5

• eplerenone
• spironolactone

Question 6

What is eplerenone? How does it work? What is it used to treat?

Answer 6

• a K+-sparing diuretic
• a competitive aldosterone receptor antagonist (specific)
• tx for:
  
  • hyperaldosteronism
  • K+ depletion
  • HF

Question 7

Dx?

• overactive ENaC –> increased Na+ resorption in the collecting tubules –> hypokalemia, metabolic alkalosis, and HTN but low aldosterone

Answer 7

Liddle Syndrome

Question 8

What are the SEs of amiloride and triamterene?

Answer 8

hyperkalemia –> arrhythmias

Question 9

Why is spironolactone anti-androgenic?

Answer 9

• it prevents testosterone synthesis by blocking 17-alpha-hydroxylase
• blocks the androgen receptor

Question 10

Aldosterone works at the _____ of the nephron, promoting Na+ reabsorption and water retention.

Answer 10

collecting duct

Question 11

Which part of the nephron is most important for K+ regulation?

Answer 11

the collecting duct

Question 12

This is the site of Na/K/H2O transport in the collecting duct.

Answer 12

the principal cells

Question 13

What is the major site of H+ secretion in the collecting duct?

Answer 13

the alpha-intercalated cell

Question 14

Aldosterone binds to _____ receptors.

Answer 14

intracellular

Question 15

______ works at the collecting duct, promoting Na+ reabsorption and water retention.

Answer 15

Aldosterone

Question 16

Aldosterone increased gene transcription to cause ____.

Answer 16

increased # of channels in the collecting duct

Question 17

What causes Liddle Syndrome?

Answer 17

it’s an auto dominant gain of function mutation

Question 18

What is the tx for Liddle Syndrome?

Answer 18

• amiloride
• triamterene

Question 19

Where does aldosterone exert its action?

Answer 19

the collecting duct

Question 20

What is Liddle Syndrome?

Answer 20

overactive ENaC –> increased Na+ resorption in the collecting tubules –> hypokalemia, metabolic alkalosis, and HTN but low aldosterone

Question 21

What is the main job of a K+-sparing diuretic?

Answer 21

• to antagonize the effects of aldosterone or ENaC

Question 22

What are the SEs of spironolactone?

Answer 22

• normal anion gap metabolic acidosis
• gynecomastia
• anti-androgen
• impotence
• decreased libido

Question 23

Why do spironolactone and eplerenone reduce morbidity and improve mortality in HF patients?

Answer 23

they reduce myocardial remodeling induced by high levels of aldosterone

Question 24

What is spironolactone? How does it work? What is it used to treat?

Answer 24

• a K+-sparing diuretic
• a competitive aldosterone receptor antagonist (nonspecific)
• tx for:
  
  • ascites
  • hyperaldosteronism
  • K+ depletion
  • HF
  • PCOS

Question 25

The potassium-sparing diuretics act upon the _____.

Answer 25

collecting duct

Question 26

Aldosterone works at the collecting duct, promoting ____ reabsorption and _____ retention.

Answer 26

Na+; water

Question 27

This is a K+-sparing diuretic that blocks Na+ reabsorption thru ENaC and is a tx for Liddle Syndrome and nephrogenic DI.

Answer 27

amiloride

Question 28

What are the potassium sparing diuretics?

Answer 28

thiazides

Question 29

What is triamterene? How does it work? What is it used to treat?

Answer 29

• a K+-sparing diuretic
• blocks Na+ reabsorption thru ENaC
• tx for:
  
  • Liddle Syndrome
  • hyperaldosteronism
  • K+ depletion
  • HF

Question 30

In a normal kidney, why is so much K+ wasted at the collecting duct?

Answer 30

because Na+ is resorbed and NOT exchanged (ENaC)

Question 31

What is amiloride? How does it work? What is it used to treat?

Answer 31

• a K+-sparing diuretic
• blocks Na+ reabsorption thru ENaC
• tx fo:
  
  • Liddle Syndrome
  • nephrogenic DI (from lithium)
  • hyperaldosteronism
  • K+ depletion
  • HF