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42 Cards in this Set
- Front
- Back
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what determines the potency of a diuretic?
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site of action
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what are the 3 key functions of the Na-K ATPase in cells of the kidney?
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- return Na to the circulation
- maintain low intracellular [Na] for passive Na entry - allow transport of other substances to be linked to Na reabsorption |
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what is the major transport mechanism in the proximal tubule? what does it do?
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- Na-H exchanger
- moves Na into the cells and H out of the cells. this facilitates reabsorption of HCO3 and Cl |
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what type of diuretic is acetazolamide?
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carbonic anhydrase inhibitor
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where does acetazolamide work?
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inhibits all steps of proximal HCO3 reabsorption
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how does acetazolamide work?
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it blocks carbonic anhydrase which makes HCO3 from H2O and CO2. HCO3 is needed for Na reabsorption
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is acetazolamide a good diuretic? why or why not?
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- no
- because there can be distal reclaimation of Na |
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what are the major side effects of carbonic anhydrase inhibitors?
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- systemic acidosis
- hypokalemia |
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what segment of the nephron is known as the diluting segment?
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the loop of henle
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what is the main ion transporter in the loop of henle?
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Na-K-2Cl cotransporter
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what are the 3 categories of loop diuretics?
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- sulfonamides
- ethacrynic acid (edecrine) - pyridine- sulfonaurea (Torsemide) |
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name the sulfonamides?
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- furosemide (Lasix)
- bumetanide |
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what differentiates the loop diuretics?
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- sulfonamides have a short duration of action
- ethacrynic acid is safe to use in patients with sulfa allergies - pyridine sulfonylurea has a long duration of action |
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why do loop diuretics have a high efficacy?
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they destroy the medullary hypertonicity
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what cell transporter do loop diuretics act on?
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the Na-K-2Cl cotransporter
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which loop diuretic has the shortest half life?
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bumetanide
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what are the major side effects of loop diuretics?
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- hypokalemia
- volume depletion/azotemia - ototoxicity - increased divalent cation excretion - allergic reactions (esp. people with sulfa drug allergies) |
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what is Bartter's Syndrome?
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an inherent defect in the activity of the Na-K-2Cl cotransporter causing NaCl wasting
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how will Bartter's Syndrome present?
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- hypokalemia
- metabolic alkalosis - hypercalciuria - normotensive |
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what microscopic changes can be seen in the nephron in a patient with Bartter's Syndrome?
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Juxtaglomerular apparatus hyperplasia
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what is the main transporter in the distal convoluted tubule?
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Na-Cl cotransporter
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where does thiazides work?
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they compete with Cl for the carrier site on the Na-Cl cotransporter in the distal convoluted tubule
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where does PTH and vitamin D act in the kidney? what do they do?
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- distal convoluted tubule
- they increase the reabsorption of Ca |
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name the thiazide drugs? which is the only one that can be used IV?
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- hydrochlorothiazide
- chlorthalidone - chlorothiazide - metolazone - indapamide - only chlorothiazide can be used IV |
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who do we give thiazides to?
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low renin hypertensives (blacks and elderly)
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T or F; thiazides work with a GFR < 30.
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false
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which class of diuretics are useful therapy for stones and nephrogenic diabets insipidus?
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thiazides
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what is the classic side effect of thiazides?
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- hyponatremia/hypokalemia
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what are the side effects of thiazides?
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- hyponatremia/hypokalemia
- adverse effects on lipid profile - impotence |
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what is Gitelman's syndrome?
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a mutation in the Na-Cl cotransporter of the distal tubule resulting in NaCl wasting, K wasting, and Mg wasting
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what is the function of the principal cells of the collecting ducts?
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fine tune Na/H2O excretion
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how do principal cells take Na out of the lumen of the collecting duct?
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via a amiloride sensitive channel
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how does aldosterone influence the principal cells?
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they increase the number and activity of Na and K channels in the principal cells
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what are the 2 ways by which K-sparring diuretics can work?
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- blockade of Na channel
- aldosterone receptor antagonism |
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how does amiloride work? what other drugs work in the same way?
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- it blocks Na channels in the collecting ducts
- Triamterene, trimethoprim, pentamidine |
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how does spironolactone work?
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it blocks the effects of aldosterone on the principal cells
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when do we use K-sparring diuretics? why?
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- in combination with other diuretics or as an adjunct for minimizing K loss
- because they have weak diuretic effects by themselves |
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what are the side effects of spironolactone?
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- gynecomastia
- hirsutism - decreased libido |
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what drug would I give a person that has lithium induced polyuria or renal Mg wasting?
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amiloride
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what effects on the heart does spironolactone have?
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- inhibits myocardial fibrosis
- improves myocardial uptake of NE |
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why would hypoalbiminemia or severe nephrotic proteinuria limit the effect of diuretics?
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because they are highly protein bound.
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T or F: this first dose of a diuretic is always the most effective.
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true; after the first dose the body will begin Na retaining responses to counteract the effects of the diuretic
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