Renal - Diuretics Flashcards
Where is ANP produced?
atrial myocytes
What are the 2 functions of ANP?
- relax smooth muscle
2. promote NaCl and water excretion by the kidney
What is the stimuli for ANP release?
Atrial stretch
increase in extracellular fluid volume
What are the actions of ANP? (5 actions)
- inhibit renin release
- increased GFR
- inhibits aldosterone secretion (via direct effect on adrenal gland and via decreased renin)
- decreases NaCl reabsorption in collecting duct
- inhibits ADH release from posterior pituitary
ANP increases GFR via vaso_____ of the afferent arteriole and vaso______ of the efferent arteriole
dilation - afferent
constriction - efferent
What is the recombinant form of the B-type natriuretic peptide?
Nesiritide (Natrecor)
What is another name for B-type natriuretic peptide?
Brain natriuretic peptide
Where is B-type natriuretic peptide produced?
ventricular myocardium
How does Nesiritide treat CHF?
causes vasodilation, diuresis, and natriuresis
T/F. Nesiritide has been linked with increased mortality and renal dysfunction
True
What level of BNP is a sign of heart failure?
> 500 pg/mL
What is a substance that increases the rate of urine volume output?
Diuretic
How do most clinically used diuretics work?
They decrease the rate of Na reabsorption of the tubules –> increased Na output (natriuresis) –> water output (diuresis)
T/F: Although many diuretics work within minutes, this effect decreases over the next few days with chronic use.
True
decreased ECF –>
decreased MAP –>
decreased GFR –>
increased renin and Angiotensin II
these effects override the effects of diuretics
6 types of diuretics
- Osmotic
- Loop
- Thiazide
- Carbonic anhydrase inhibitors
- Aldosterone antagonists
- Na channel blockers
3 examples of osmotic diuretics
- urea
- mannitol
- glucose in diabetics who spill glucose into their urine –> increased UOP
How does an osmotic diuretic work
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
3 examples of Loop diuretics
- Lasix
- Bumex
- Ethacrynic acid
How do loop diuretics work?
inhibit the Na-2Cl-K co-transporter in the TAL –> increased delivery of [osmotic] solutes to distal tubule –> fluid is drawn into the tubules
How do loop diuretics influence the countercurrent multiplier system?
They disrupt it because solutes can’t be drawn out of the filtrates back into the interstitium –> interstitium cannot become hyperosmolar
How do thiazide diuretics work?
Name a thiazide diuretic (it’s easy)
inhibit NaCl reabsorption in the early distal tubule
hydrochlorothiazide
Name a carbonic anhydrase inhibitor
Acetazolamide (Diamox)
How do Carbonic anhydrase inhibitors work?
decrease bicarb and Na reabsorption
bicarb reabsorption is coupled to Na reabsorption in the proximal tubule via Na-H counter-transport
What is the main disadvantage to a carbonic anhydrase inhibitor?
It causes acidosis through bicarb loss in urine
Name an aldosterone antagonist
spironolactone (aldactone)
How do aldosterone antagonists work?
decrease
- reabsorption of Na and
- secretion of K by competing for aldosterone binding sites in the distal tubule
What is unique about Na channel blockers and aldosterone antagonists?
They are potassium sparing
Name 2 Na channel blockers
amiloride and triamterene
How do Na channel blockers work?
decrease activity of NaK pump in collecting tubules –> decreased Na reabsorption
