32 - Renal drugs Pt. 3

Question 1

Most common Renal Na channel (ENaC) blocker?

Answer 1

amiloride

Question 2

Renal Na channel blockers act where?

Answer 2

distal convoluted tubule

Question 3

Renal Na channel is luminal or basolateral?

Answer 3

luminal. the K channel is basolateral, and retains K in blood when Na channel is blocked (no electric gradient created on luminal side)

Question 4

For renal Na channels blockers, most ion excretions go down or up? what are the exceptions?

Answer 4

• Down
• Na & Cl go up
• HCO3, N2PO4, uric acid unaffected

Question 5

which na channel blocker has long half life for clinical use?

Answer 5

amiloride

Question 6

Treat Liddle’s syndrome w/ what diuretics?

Answer 6

renal Na channel blockers

Question 7

5% afrincan americans have a polymorphism that makes which diuretics extra potent?

Answer 7

ENaC

Question 8

which ENaC blocker (Renal Na channel blocker) is also a folate antagonist?

Answer 8

Triamterene

Question 9

mineralocorticoid antagonists have what mech?

Answer 9

block mineralocorticoid receptor (stop Na reabsorption only).

Question 10

mineralocorticoids are almost the same as what class?

Answer 10

ENaC blockers

Question 11

How are mineralocorticoids different from ENaC blockers?

Answer 11

• Don’t have to enter tubular lumen to work
• mech
• Rest is same

Question 12

How do mineralocorticoids normally act?

Answer 12

In nucleus: up transcription of AIP (aldosterone-induced proteins). These activate previously silent Na channels & pumps.

Question 13

which mineralocorticoid antag has possible malignancies from chronic use?

Answer 13

spironolactone

Question 14

which mineralocorticoid antag is treatment for primary and secondary hyperaldosteronism, and for ascites/edema from cirrhosis?

Answer 14

spironolactone

Question 15

Which has more systemic effects? V1 or V2?

Answer 15

V1. [that’s why we use desmopressin, not vasopressin as antidiuretic]

Question 16

How do V1 receptors work?

Answer 16

down renal blood flow-> up salt gradient

Question 17

How do V2 receptors work? (3)

Answer 17

H2O reabsorption up in distal tubule & collecting duct in 3 ways:

• up aquaporins
• up permeability to urea
• up Na/K/2Cl symporter activity

Question 18

Xanthine oxidase (inhibited by allopurinol) normally does what?

Answer 18

converts xanthine to urate

Question 19

probenecid inhibits excretion of other diuretic drugs. this means the diuretics will work better or worse?

Answer 19

WORSE! have to get to lumen to work.

Question 20

what’s probenecid’s biphasic effect on gout?

Answer 20

• stoops urate excretion first…

- then prevents its reabsorption.