Diuretics: Ch. 2.1- Acetazolamide, mannitol Flashcards
By the end of the proximal convoluted tubule, the concentration of ______ is decreased.
most solutes
By how much is the concentration of filtered sodium decreased by the end of the proximal convoluted tubule?
66%
Carbonic anhydrase inhibitors, such as ______, cause sodium and bicarb to stay in the lumen leading to urine alkalization.
acetazolamide
The buildup of bicarb in the tubule _____ the pH of the urine.
increases
What does water always follow?
Na+
What is reabsorbed at the end of the proximal convoluted tubule?
bicarb
The H2O + CO2 produced by carbonic anhydrase (H2CO3) diffuse into the ______.
intracellular space
Where are Na+/K+ ATPase pumps located?
on the basolateral membrane
_____, such as acetazolamide, cause sodium and bicarb to stay in the lumen leading to urine alkalization.
Carbonic anhydrase inhibitors
What are the SEs of acetazolamide?
- K+ wasting (hypokalemia)
- type 2 renal tubular acidosis
- increased calcium phosphate stone formation
- they’re sulfa drugs (= hypersensitivity rxns)
Cue:
- mom at the vending machine taking away peanuts and giving her son a banana
- vending machine = Na+/K+ ATPase (pump) on the basolateral membrane
- taking away peanuts = taking away Na+
- giving banana = giving K+
- *** The Na+/K+ ATPase pumps 3 Na+ out and 2 K+ in.
Cue:
- helmets labeled “H+”
protons
Cue:
- peanuts
salt (Na+)
Cue:
- 3 batteries powering a banana vending machine
- 3 batteries = 3 ATPs
- banana = K+
- vending machine = Na+/K+ ATPase (pump) on the basolateral membrane
What is the function of the proximal convoluted tubule?
reabsorption
Cue:
- pro-cart track
proximal convoluted tubule
Where in the nephron does mannitol exert its effects?
- in the proximal convoluted tubule
- in the descending limb of the Loop of Henle
What is resorbed at the proximal convoluted tubule?
- electrolytes (Na+, Cl-, K+)
- organic solutes (glucose, amino acids)
Carbonic acid (H2CO3) –> ____ + ____
H2O + CO2
By how much is the concentration of bicarb increased at the end of the proximal convoluted tubule?
85%
Cue:
- batteries
ATP
H+ + HCO3- = ______
carbonic acid (H2CO3)
Is acetazolamide K+ sparing or wasting? Why?
- wasting
- bc Na+ is spared
Why is bicarb reabsorbed in the proximal convoluted tubule?
to maintain acid-base status
What is the normal intracellular concentration of Na+ in the renal ? Why?
- low
- to allow for increased renal tubule absorption
What kind of acid/base change do carbonic anhydrase inhibitors, such as acetazolamide, cause?
a normal anion gap metabolic acidosis
Carbonic anhydrase inhibitors, such as acetazolamide, cause sodium and bicarb to stay in the lumen leading to _____.
urine alkalization
How does mannitol work in the kidney?
it remains in the lumen –> water is pulled into the lumen towards it (osmotic diuresis)
Cue:
- track worker standing at the edge of the yellow/gray tracks handing out peanuts to the gray side and letting H+ helmets back into the yellow side
- track worker = Na+/H+ exchanger
- peanuts = Na+
- H+ helmets = protons
- *** Na+/H+ exchanger is located on the apical membrane
By how much is the concentration of filtered glucose and amino acids decreased by the end of the proximal convoluted tubule?
all
Cue:
- bananas
potassium (K+)
Which diuretics exert their effects at the proximal convoluted tubule?
- acetazolamide
- mannitol
What is the function of the Na+/H+ exchanger?
allows bicarb reabsorption at the proximal convoluted tubule
At which site in the nephron do acetazolamide and mannitol exert their effects?
at the proximal convoluted tubule
What is mannitol? What is it used to treat?
- an osmotic diuretic
- tx for:
- elevated intracranial pressure
- elevated intraocular pressure/glaucoma
Excessive bicarb depletion leads to _____.
excessive Na+/Cl- reabsorption
The Na+/K+ ATPase pumps ____ out and _____ in.
- 3 Na+ out
- 2 K+ in
Carbonic anhydrase inhibitors, such as acetazolamide, cause ______ to stay in the lumen leading to urine alkalization.
sodium and bicarb
What are the s/s of acute mountain sickness?
- weakness
- insomnia
- dizziness
- HA
- nausea
- pulm/cerebral edema
By how much is the concentration of potassium decreased by the end of the proximal convoluted tubule?
65%
What are carbonic anhydrase inhibitors used for? Name 1 example.
- tx for:
- glaucoma (decrease aqueous humor production)
- idiopathic intracranial HNT aka pseudotumor cerebri (decreased CSF production)
- tx and prevention of:
- acute mountain sickness
- gout
- uric acid stones/cystenuria
- one ex: acetazolamide
Cue:
- yellow and gray race tracks separated by a divider
- yellow = lumen of the renal tubule
- gray = intracellular compartment of the tubule epi cells (next to the interstitium)
- divider = basolateral membrane where Na+/K+ ATPases are located
Cue:
- biCARb race car on the yellow track
- bicarb = HCO3-
- yellow track = lumen of the prox. convoluted tubule (PCT)
How does acetazolamide work?
it inhibits carbonic anhydrase –> no bicarb reabsorption
This drug inhibits carbonic anhydrase –> no bicarb reabsorption.
acetazolamide
What are the SEs of mannitol?
- pulmonary edema
- heart failure exacerbation
- hypernatremia –> severe dehydration
