Renal - Diuretics

Question 1

Where is ANP produced?

Answer 1

atrial myocytes

Question 2

What are the 2 functions of ANP?

Answer 2

1. relax smooth muscle

2. promote NaCl and water excretion by the kidney

Question 3

What is the stimuli for ANP release?

Answer 3

Atrial stretch

increase in extracellular fluid volume

Question 4

What are the actions of ANP? (5 actions)

Answer 4

1. inhibit renin release
2. increased GFR
3. inhibits aldosterone secretion (via direct effect on adrenal gland and via decreased renin)
4. decreases NaCl reabsorption in collecting duct
5. inhibits ADH release from posterior pituitary

Question 5

ANP increases GFR via vaso_____ of the afferent arteriole and vaso______ of the efferent arteriole

Answer 5

dilation - afferent

constriction - efferent

Question 6

What is the recombinant form of the B-type natriuretic peptide?

Answer 6

Nesiritide (Natrecor)

Question 7

What is another name for B-type natriuretic peptide?

Answer 7

Brain natriuretic peptide

Question 8

Where is B-type natriuretic peptide produced?

Answer 8

ventricular myocardium

Question 9

How does Nesiritide treat CHF?

Answer 9

causes vasodilation, diuresis, and natriuresis

Question 10

T/F. Nesiritide has been linked with increased mortality and renal dysfunction

Answer 10

True

Question 11

What level of BNP is a sign of heart failure?

Answer 11

> 500 pg/mL

Question 12

What is a substance that increases the rate of urine volume output?

Answer 12

Diuretic

Question 13

How do most clinically used diuretics work?

Answer 13

They decrease the rate of Na reabsorption of the tubules –> increased Na output (natriuresis) –> water output (diuresis)

Question 14

T/F: Although many diuretics work within minutes, this effect decreases over the next few days with chronic use.

Answer 14

True

decreased ECF –>
decreased MAP –>
decreased GFR –>
increased renin and Angiotensin II

these effects override the effects of diuretics

Question 15

6 types of diuretics

Answer 15

1. Osmotic
2. Loop
3. Thiazide
4. Carbonic anhydrase inhibitors
5. Aldosterone antagonists
6. Na channel blockers

Question 16

3 examples of osmotic diuretics

Answer 16

1. urea
2. mannitol
3. glucose in diabetics who spill glucose into their urine –> increased UOP

Question 17

How does an osmotic diuretic work

Answer 17

They’re filtered from the bloodstream into bowman’s capsule and are not easily reabsorbed.
They’re big, heavy molecules and therefore draw fluid into the tubules

Question 18

3 examples of Loop diuretics

Answer 18

1. Lasix
2. Bumex
3. Ethacrynic acid

Question 19

How do loop diuretics work?

Answer 19

inhibit the Na-2Cl-K co-transporter in the TAL –> increased delivery of [osmotic] solutes to distal tubule –> fluid is drawn into the tubules

Question 20

How do loop diuretics influence the countercurrent multiplier system?

Answer 20

They disrupt it because solutes can’t be drawn out of the filtrates back into the interstitium –> interstitium cannot become hyperosmolar

Question 21

How do thiazide diuretics work?

Name a thiazide diuretic (it’s easy)

Answer 21

inhibit NaCl reabsorption in the early distal tubule

hydrochlorothiazide

Question 22

Name a carbonic anhydrase inhibitor

Answer 22

Acetazolamide (Diamox)

Question 23

How do Carbonic anhydrase inhibitors work?

Answer 23

decrease bicarb and Na reabsorption

bicarb reabsorption is coupled to Na reabsorption in the proximal tubule via Na-H counter-transport

Question 24

What is the main disadvantage to a carbonic anhydrase inhibitor?

Answer 24

It causes acidosis through bicarb loss in urine

Question 25

Name an aldosterone antagonist

Answer 25

spironolactone (aldactone)

Question 26

How do aldosterone antagonists work?

Answer 26

decrease

• reabsorption of Na and
• secretion of K by competing for aldosterone binding sites in the distal tubule

Question 27

What is unique about Na channel blockers and aldosterone antagonists?

Answer 27

They are potassium sparing

Question 28

Name 2 Na channel blockers

Answer 28

amiloride and triamterene

Question 29

How do Na channel blockers work?

Answer 29

decrease activity of NaK pump in collecting tubules –> decreased Na reabsorption