Renal 1 Flashcards
What do the kidneys regulate?
- fluid
- acid-base
- electrolyte/ion balance
How much of the glomerular filtrate is reabsorbed?
> 99%
Describe the structure of a nephron
glomerulus –> proximal tubule –> loop of Henle –> distal convoluted tubule –> collecting duct
What are glomerular capillaries permeable to? impermeable to?
permeable to water
impermeable to plasma proteins
What is the function of diuretic?
- decrease reabsorption of Na+ (and Cl-) in the kidney
- increase excretion of urinary NaCl –> secondary water loss
What is the use of a diuretic?
alter volume/composition of bodily fluids
Where do diuretics act?
- directly on cells of nephron
- indirectly by modifying content of the filtrate
What are the classes of diuretics?
1) sodium-glucose cotransporter-2 (SGLT2) inhibitors
2) loop diuretics
3) thiazides
4) K+ sparing diuretics
5) antidiuretic hormone antagonists
Where are SGLT2 found?
APICAL membrane of cells in PROXIMAL convoluted tubule
What is the function of SGLT2?
reabsorption of glucose and Na+
What is the function of SGLT2 inhibitor?
reduce reabsorption of glucose and Na
What are SGLT2 inhibitors mainly used to treat?
type II diabetes
Why is SGLT2 inhibitor not used in hypertension?
reduce reabsorption of glucose
What are SGLT2 inhibitors used to treat (besides diabetes)?
heart failure in diabetes patients at risk for CV disease
How do SGLT2 inhibitors treat heart failure?
improvement in cardiac energy metabolism (ketone oxidation in heart)
What are the SGLT2 inhibitors have been shown to treat heart failure in diabetes patients?
- empagliflozin
- canagliflozin
- dapagliflozin
Which SGLT2 inhibitor treats heart failure in diabetes patients with atherosclerotic cardiovascular disease?
dapagliflozin
Which SGLT2 inhibitor treats heart failure in diabetes patients with cardiovascular disease?
- empagliflozin
- canagliflozin
Which limb of the loop of henle is responsible for water reabsorption?
descending limb
Which part of the loop of henle is relatively water impermeable?
thin ascending limb
Which part of the loop of henle reabsorbs ~25% Na+ and is nearly impermeable to water?
thick ascending limb
Which transporter is found at the apical membrane of the thick ascending limb of the loop of henle? which way do the ions flow?
Na/K/2Cl cotransporter (NKCC2); all flow into loop of henle cell
note: excessive K+ accumulation inside cell
Which transporter is found at the basolateral membrane of the thick ascending limb of the loop of Henle? Which way do the ions flow?
K/Cl cotransporter; ions flow into interstitium/blood
What is the net electrical potential of the lumen at the thick ascending limb of the loop of henle? What causes this? What does this electrical potential lead to?
net potential: (+)
cause: diffusion of K+ into lumen via apical K+ channels
leads to: driving force for reabsorption of cations
Which drug acts as a loop diuretic?
furosemide
What class of diuretic is the most efficacious?
loop diuretics
What is the mechanism of loop diuretics?
inhibit NKCC
What are the effects of using loop diuretics?
- reduced Na and Cl reabsorption
- diminished luminal (+) potential, reduced Ca and Mg reabsorption
What are the therapeutic uses of loop diuretics?
acute pulmonary edema, chronic HF, hypertension, acute renal failure, acute hypercalcemia, hyperkalemia
What are the adverse effects of loop diuretics?
- hypokalemia, hypomagnesemia
- metabolic alkalosis
- ototoxicity (due to changes in electrolyte composition of endolymph in the inner ears, high K+)
