Drugs Acting on the Kidney Flashcards
diuretics act mainly on which ion?
Na
another word for vasopressin
ADH
main drug class that acts on the kidney?
diuretics
what do diuretics do?
increase urine flow by inhibiting reabsorption of sodium in the kidney
what causes oedema
imbalance between the rate of formation and absorption of interstitial fluid
what forces are affected in oedema?
starling forces
what starling forces control movement of water OUT of the capillary?
hydrostatic pressure in the capillary
oncotic pressure of the interstitium
which oncotic pressure has the highest pressure and why?
capillary oncotic pressure as it has more plasma proteins
oedema will occur if capillary oncotic pressure ___
decreases
oedema will occur if hydrostatic pressure in the capillary ___
increases
where does protein go in nephrotic syndrome?
the filtrate (urine)
what does albumin do?
sets the oncotic pressure of the plasma
what happens to the osmotic pressure of the plasma in nephrotic syndrome and why?
will decrease as you are losing albumin
what happens when osmotic pressure of the plasma decreases?
increased formation of interstitial fluid will occur -> oedema
what effect does increased interstitial fluid have on blood flow?
will decrease BV and CO
what effect does decreases blood flow have on RAAS?
will upregulate it and cause salt retention
what effect does RAAS have on the capillary hydrostatic pressure?
increases it
what effect does RAAS have on plasma oncotic pressure?
decreases it further
what effect does increased capillary hydrostatic pressure and decreased plasma oncotic pressure have on the body?
oedema
why do you get oedema in ascites?
increased capillary hydrostatic pressure in portal vein but have decreased albumin production (lose protein)
what parts of the nephron do thiazide diuretics have an effect on?
Na/Cl co-transport in the DISTAL convoluted tubule
carbonic hydrase inhibitors block which process in the nephron?
Na/H exchange in proximal and distal convoluted tubules
what 2 conditions are carbonic anhydrase inhibitors mainly used in?
glaucoma
altitude sickness
what process in the nephron do loop diuretics block?
triple cotransporter (Na/K/Cl) in the thick ascending limb of the loop of henle
main complication of diuretics is…
hypokalaemia
what is the main site of action of most diuretics?
apical membrane of tubular cells
drug bound protein will not be filtered at the glomerulus T or F
T
how do diuretics get into the tubule to be able to work at the apical membrane?
if not bound to plasma protein -> glomerular filtration
if bound -> secretion via active transport at proximal tubule
an anion is acidic or basic?
acidic
a cation is acidic or basic?
basic
loop diuretics and thiazides are acidic or basic?
acidic
what part of the triple cotransporter do loop diuretics bind to?
Cl site
how is the triple co-transporter electrically neutral?
Cl has 2 negative charges
Na and K have 1 positive charge each
loops diuretics cause Ca and Mg ___
loss
what happens t to the Na that has entered via the triple cotransporter?
is used for the Na/K pump
what happens to the K that has entered via the triple cotransporter?
is used for either:
the Na/K pump
the K/Cl pump
what happens to the Cl that has entered via the triple cotransporter?
is used for either:
the K/Cl pump
Cl only channel
how is digoxin more toxic if a patient is on a loop diuretic?
digoxin competes against K+ at the ATPase so if K is low (with diuretic) more digoxin will bind
what acid base imbalance can you get with loop diuretics?
metabolic alkalosis
what site of the Na/Cl carrier do thiazide diuretics bind?
Cl part
thiazides are used in…
mild heart failure
hypertension
severe resistant oedema
how do diuretics cause hypokalaemia?
diuretic causes inc Na load
more Na reaborbed so more K secreted into urine
aldosterone makes more __ channels available
ENAC
what channels do spirinolactone and epleronone block?
ENAC
what diuretic can cause hyperkalaemia?
ENAC (aldosterone channel) blockers eg spirinolactone
when should you give spirinolactone?
along with a loop to prevent K loss
osmotic diuretics do not have a specific target T or F
T
presence of mannitol (an osmotic diuretic) ___ the osmolarity of the filtrate
increases
most iso-osmotic reabsorption of water occurs in…
the proximal tubule
how do osmotic diuretics enter the nephron?
via glomerular filtration
name 2 conditions that osmotic diuretics are used in
acute hypovolaemic renal failure
acute raised intracranial/ocular pressure
depletion of what ion is an adverse effect of osmotic diuretics?
Na
loss of bicarbonate results in a/an ___ diuresis
alkaline
why are carbonic anhydrase inhibitors used in glaucoma?
suppress formation of aqueous humour to reduce intraocular pressure
what are ENAC channels?
epithelial Na channels
what is neurogenic diabetes insipidus?
lack of ADH secretion from posterior pituitary
what treats diabetes insipidus?
desmopressin
what is nephrogenic diabetes insipidus?
inabiity of the nephron to respond to vasopresin
mutations in what receptor causes nephrogenic diabetes insipidus?
V2 receptor gene
nicotine ___ ADH secretion
enhances
what do aquaretics do?
act as competitive antagonists of ADH
cause excretion of water only
what do V1 receptors do?
mediate vasoconstriction
what do V2 receptors do?
mediate water reabsorption
blocking V2 receptors __ plasma Na conc
increases
aquaretics are used in what conditions?
SIADH
2 locations of SGLT1 receptors
intestine
kidney
location of SGLT2 receptors?
proximal tubule of kidney
which SGLT receptor has a higher affinity for glucose?
SGLT1
which SGLT receptor has the highest transport capacity?
SGLT2
main problem of NSAIDs in kidneys?
affect the blood supply to the kidney by inhibiting COX
what do prostaglandins do in the kidney?
control blood supply to (vasodilate) the kidney
PGE2 is a prostaglandin mediating blood supply to what area of the kidney?
medulla
PGI2 is a prostaglandin mediating blood supply to what area of the kidney?
glomeruli
prostaglandins are sythesised in response to what stimuli?
ischaemia mechanical trauma angiotensin 2 ADH bradykinin
what part of the kidney do prostaglandins dilate?
afferent arteriole
constriction of the efferent arteriole is done by…
angiotensin 2
what does allopurinol do?
inhibits urate synthesis
