Drugs acting on the kidney Flashcards
Which transporter do loop diuretics act on?
Na+/K+/2Cl-
Where do loop diuretics act?
thick ascending limb of the loop of henle
What are 2 examples of loop diuretics?
Furosemide
Bumetanide
Where do thiazide diuretics act?
Distal convuluted tubule
What transporter do thiazide diuretics act on?
Inhibit the Na+/Cl- co transporter
What are 2 examples of thiazide diuretics?
bendrofluethiazide, indapimide, metolazone
Where to potassium sparing diuretics act?
Collecting tubules
Where do the hormones aldosterone and vasopressin/ADH act?
collecting tubules
What does the hormone aldosterone do?
up regulates the activity of Na+/K+ pumps in the collecting ducts and distal convulted tubule.
This results in the reabsorption of Na+ into the plasma and the secretion of K+ into the urine.
What is the mechanism of the potassium sparing diuretics?
Inhibits action of aldosterone on the Na+/K+ in the collecting tubules. Prevents the secretion of K+ and the reabsorption of Na+.
What do diuretics achieve?
Lower plasma levels of Na+ (hyponatraemia)
Promote diuresis and therefore lower BP
What are 2 potassium sparing diuretics?
spironolactone, eplerenone, Amiloride
What are the two main concerns with potassium sparing diuretics?
Gynaecomastia (anti androgenic effect)
Hyperkalaemia leading to metabolic acidosis
Which substance is 100% absorbed in the kidneys in a normal healthy person?
glucose
Where is glucose and amino acids reabsorbed?
proximal convulted tubule
How is urine acidified?
Acidification mainly takes place in the collecting tubule and this is via the secretion of H+ and K+ ions into the urine.
Where do carbonic anyhydrase inhibitors act?
proximal convuluted tubule
What is the mechanism of carbonic anyhydrase inhiitors?
block the reaction of carbon dioxide and water to H+.
This prevents Na+/H+ exchange in the proximal convuluted tubule.
This lowers Na+ reabsorption (as Na+ is usually reabsorbed in order to secrete H+)
How do osmotic diuretics work?
The remain in the tubule as they are freely filtered at the glomerulus but poorly reabsorbed. This pulls water to be reabsorbed.
In which part of the kidney is sodium reabsorbed the most?
Proximal convulted tubule (65%), Loop of henle (25%),
How does vasopressin/ADH regulate water?
V2 stimulation leads to vesicles containing water channels bind to the membranes of cells in the collecting duct cells.
This leads to the reabsorption of water.
V1 receptor stimulation results in vasoconstriction, therefore lowering the amount of plasma filtered.
V1 also enhances the action of aldosterone
