Diuretics & ADH - Full PPT Flashcards
Where do Carbonic Anhydrase Inhibitors act?
Proximal tubule
ex. Acetazolamide
Is acetazolamide used as a kidney diuretic?
No, not a clinical use
Where do loop diuretics act?
Ascending loop of Henle
How useful are loop diuretics?
Extremely!
What do Loop diuretics do (mech.)?
Inhibit Na, K, 2 Cl transporter
Where do Thiazide diuretics act?
DCT (distal convoluted tubule)
What are Thiazide diuretics extremely useful for?
Hypertension
What do thiazide diuretics do?
Inhibit NaCl symporter
Where do Potassium sparing diuretics work?
In Cortical collecting tubule
What are K+ sparing diuretics useful for? What are their mechanisms?
-Useful for prevention of K+ loss
-Either:
1. Inhibit aldosterone receptors
OR
2. Block Na exchange for K and H
Where does AHD work? What does it do?
Works in medullary collecting duct.
Acts to recruit aquaporin channels.
Where do osmotic diuretics work?
Proximal tubule and/or descending limb of the loop of Henle
What two Loop Diuretics must you know?!
Furosemide (Lasix)
Bumetanide
What is the mechanisms of Loop Diuretics?
Inhibit Na, K, 2 Cl transporter in the ascending loop of Henle
Normally the ascending loop of Henle accounts for how much of the Na+ reabsorption?
25%
How do loop diuretics influence ions?
-Tubular fluid becomes hypo-osmolar as Na, K and Cl are pumped out but water remains inside (no aquaporins here!)
What od loop diuretics prevent?
Decrease in osmolarity –> results in greater retention of ions and water in later segments of nephron
What effect do loop diuretics have on urine composition?
- Inc. NaCl excretion
- Inc. K excretion
- -> Some increased nephron Na is exchanged for K in the collection tubule
What side effect can loop diuretics cause by altering K+ concentration?
They decrease K+ concentration in body (inc. in urine) which can cause K+ to be too low in the cochlea and inhibit hearing.
What are the therapeutic uses of Loop Diuretics?
- Pulmonary edema
- Other edematous conditions
- Hyperkalemia
- Acute renal failure
- Anion overdose (Bromide, Fluoride, and Iodide)
How do loop diuretics compare in terms of effect to thiazides?
Loop diuretics work earlier in the tubule than thiazide diuretics so more Na+ and Cl- gets absorbed here and these drugs have larger effect!
What are the three thiazide diuretics?
Chlorathalidone
Hydrochlorothiazide
Metalazone
What is the mechanism of thiazide diuretics and where do they work?
Block NaCl transporter in the DCT
What does blocking the NaCl transporter cause?
- NaCl transporter normally accounts for 8% of NaCl reabsorption
- Block of this transport mechanism results in excretion of water, Na, Cl and K in urine
- K gets excreted because some of the increased Na is exchanged for K in the cortical collecting tubule