27 - diuretics Flashcards
what happens if we block Na+ reabsorption into the blood
more water leaves in urine
lowers BP
Kidneys filter 180 liters of plasma per day
Produce _ liters of urine per day
1.5 liters of urine
<1% of volume is excreted via urine
Carbonic Anhydrase facilitates Na+ and -
HCO3 _
(and H2O _)
Na+ and -
HCO3 reabsorption
H2O retention
Carbonic anhydrase activity will: 1. Provide protons for H+/Na+ exchange 2. Provide HCO3 - for Na+ cotransport to blood
net? CO2 plus water from lumen yields _ in blood and _ in urine
Net: CO2 plus water from lumen yields Na+CO3 in
blood;
H+ in urine
Inhibition of carbonic anhydrase inhibits _ reentry
and enhances _ loss, water follows Na+
inhibits Na+ reentry
(and enhances fluid loss, water follows Na+)
decreasing volume thus decreasing BP
where do carbonic anhydrase inhibitors (diuretic) site of action
proximal convolutaed tubule
most of Na is reabsorbed here and it blocks the reuptake of Na leading to more sodium in urine (means more water leaving)
_ diuretic is a type of diuretic that inhibits reabsorption of water and sodium. They are
pharmacologically inert substances that are given intravenously. They increase the osmolarity of blood
and renal filtrate. Two examples are mannitol and
isosorbide.
An osmotic diuretic
*mannitol filtered out but not well resorbed
water follows mannitol - which is in urine
where do osomtic diuretics site of action
what part of nephron
PCT, thin descending and thin ascending limbs
water follows mannitol
where do loop diuretics works in the nephron
thick ascending limb
Loop diuretics are diuretics that act at the
ascending loop of Henle in the kidney on _. They are primarily used in medicine to treat _ and _ often due to congestive heart failure or
renal insufficiency.
inhibs Na,K,2Cl symporter - significantly increases the excretion of these ions
hypertension
and edema
_ diuretics are
more effective in patients with normal kidney function,
_ diuretics are more effective in patients with impaired kidney function
thiazide diuretics - normal healthy kidneys
loop diuretics - impaired kidney patients
_ diuretics
inhibits Na,K,2Cl symporter - significantly increases the excretion of these ions - water follows
loop diuretics
sulfonamide allery is a drug allery linked with use of _ diuretics
Ca and Mg are excreted as well so have to be careful about imbalances
loop diuretics
sulfonamide is in some antibiotics
these diuretics work in the DCT , only 5-10% of Na reaborbed here
block the Na/Cl symporter, increasing Na and Cl excretion and water
thiazide diuretics
secreted by PCT but works in the DCT
can have weak CA-I effect as well
Because loop and thiazide diuretics increase
sodium delivery to the distal segment of the
distal tubule, this increases _ loss,
the increase in distal tubular sodium concentration
stimulates the _-sensitive sodium
pump to increase sodium reabsorption in
exchange for potassium and hydrogen ion,
which are lost to the urine.
The increased
hydrogen ion loss can lead to metabolic
alkalosis. Part of the loss of potassium and
hydrogen ion by loop and thiazide diuretics
results from activation of the reninangiotensin-aldosterone system that occurs
because of reduced blood volume and arterial
pressure.
increases potassium loss(potentially causing hypokalemia)
aldosterone - stimulates Na/K ATPase
Increased aldosterone stimulates
_ reabsorption and increases _ and _ ion excretion into the urine.
sodium reabsorption (water comes back in)
potassium
and hydrogen ion excretion
_ diuretics work in collecting tubules and inhib Na channels or work on ADH receptor
potassium-sparing
inhib apical Na channel
antagonist to ADH - binds to its recept to decrease gene expression and reduce synthesis of Na channels in tubule or decreases # of Na/K ATPase pumps in basolateral membrane
_ diuretics are diuretic drugs that do not
promote the secretion of potassium into the urine.
They are used as adjunctive therapy, together with other drugs,
in the treatment of hypertension and management of
congestive heart failure.
Potassium-sparing
The combination therefore helps maintain a normal
reference range for potassium.
_ diuretics
inhib apical Na channel blocking reabsorption
antagonist to ADH - binds to its recept to decrease gene expression and reduce synthesis of Na channels in tubule or decreases # of Na/K ATPase pumps in basolateral membrane
K sparing
used as ADJUNCTIVE THERAPY
This prevents sodium re-absorption and
potassium and hydrogen ion secretion.
K sparing diuretics
binding to ADH receptor prevents the production of proteins that are normally
synthesized in reaction to aldosterone. These mediator proteins are not
produced, and so stimulation of sodium-potassium exchange sites in the
collection tubule does not occur. This prevents sodium re-absorption and
potassium and hydrogen ion secretion.
_ diuretic
PCT, Loop of Henle, Collecting duct
inhibition of water and Na reabsorption
osmotic
can really increase the production of urine - literally loss 20 pounds in 1-2 ddays
_ diuretic
PCT
inhibition of bicarbonate reabsorption
carbonic anhydrase inhibitors (CA-I)
_ diuretic
thick ascending limb
inhib of Na,K,Cl cotransport
loop diuretics
Indirect effect - inhibit recapturing Mg and K+ = therapeutically - can lead to Mg and Ca imbalances - loop diuretics
_ diuretic
early distal tubule
inhib of Na,Cl contransport
Thiazide
_ diuretic
late distal tubule, Collecting duct
inhibition of Na+ reabsorption and K+ secretion (keeps K)
K sparing diuretics
Blood goes into the _ and is filtered
Everything gets filters exceppt proteins
Then things get selectively put back into blood
Blood pressure needs to be there for this to work
Kidney regulates blood pressure as well
glomerulus
Because of location of action Both _ and _ diuretics increase potassium loss
Take potassium Cl pill - banana won’t give enough
So if patient is taking potassium Cl pill - they are probably taking a BP med that is depleting of K because keeping Na out
Becasuse of this = Stimulates a Na pump to increase sodium resorption in exchange for K and protons This pump is sensitive to aldosterone
loop and thiazide
why it is nice to give K sparing diuretics in addition(decrease biosynthesis of the channel for Na and K
