1: Drugs acting on the kidney 1 & 2 Flashcards Preview

Renal Week 4 2017/18 > 1: Drugs acting on the kidney 1 & 2 > Flashcards

Flashcards in 1: Drugs acting on the kidney 1 & 2 Deck (58)
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1

What is a diuretic?

Prevents reabsorption of electrolytes (usually sodium) causing diuresis (because water follows sodium)

2

What is ADH?

What is its other name?

Anti-diuretic hormone

Acts on V2 receptors (G-protein coupled) to increase water reabsorption

Vasopressin

3

How do SGLT2 inhibitors work?

What symptom do they cause?

Inhibit combined glucose-sodium transporter

Glycosuria

4

What are uricosuric drugs?

Stimulate excretion of uric acid into tubules

5

Diuretics (increase / decrease) urine flow.

increase urine flow

6

What is

a) hydrostatic

b) osmotic/oncotic pressure?

hydrostatic pressure - pressure of the fluid in a tube pushing outwards

oncotic pressure - negatively charged plasma proteins in the blood pulls fluid from the interstitium

so oncotic pressure opposes hydrostatic pressure

7

What change in forces causes oedema?

Increase in capillary hydrostatic pressure

and/or

Decrease in capillary oncotic pressure

8

How does nephrotic syndrome cause oedema in the short and long-term?

Proteinuria

Less protein in the blood

So less oncotic pressure pulling fluid back into the capillaries

So more fluid in the interstitium

(Also: blood volume & pressure drop, RAAS increases BP and BV (aldosterone), capillary hydrostatic pressure increases and oncotic pressure decreases because there's even less protein in blood = even more fluid in the interstitium)

OEDEMA

9

How does CCF cause oedema?

Reduced cardiac output

Renal hypoperfusion

RAAS 

BV, BP increases

So hydrostatic pressure increases and oncotic pressure decreases (dilution)

OEDEMA

10

How does cirrhosis cause oedema?

What is abdominal oedema called?

Portal hypertension increases hydrostatic pressure

Liver can't produce albumin, so oncotic pressure decreases

Plus RAAS activates because blood volume decreases...

OEDEMA

(Ascites)

11

Where in the nephron is sodium reabsorbed?

Proximal tubules (passively, along with Cl-)

Ascending limb (triple transporter)

Distal tubules (Na+/Cl- co-transporter)

Collecting tubules (Na+/K+ exchange)

12

How is sodium reabsorbed in the

a) proximal tubules

b) ascending limb

c) distal tubules

d) collecting ducts?

a) Passively

b) Triple transporter

c) Na/Cl co-transport

d) Na/K exchange

13

Which drugs block sodium reabsorption in the

a) proximal tubules

b) ascending limb

c) distal tubules

d) collecting ducts?

a) Carbonic anhydrase inhibitors (minor)

b) Loop diuretics (block triple transporter)

c) Thiazide thiazide-like diuretics (block Na/Cl co-transporter)

d) Potassium-sparing diuretics (e.g spironolactone)

14

As sodium reabsorption is paired to potassium secretion in the collecting ducts, what happens to [K+] if you give a patient

a) thiazide diuretics

b) loop diuretics

c) spironolactone

a) Decreases

b) Decreases

c) Spared, actually increases as a result

15

What percentage of sodium is reabsorbed by the glomeruli?

99%

diuretics still cause massive changes in sodium conc. in the urine

16

By which two routes could diuretics enter the urine?

Why is one far more common than the other?

1. Filtration at glomerulus

2. Secretion from peritubular capillaries into proximal tubules

Drug is usually bound to protein so it can't be filtered

17

What are

a) positive

b) negative ions called?

a) Cations

b) Anions

18

What transporters carry

a) acidic diuretics like thiazides and loop drugs

b) basic diuretics?

a) Organic ANION transporters

b) Organ CATION transporters

because acids are negatively charged and bases are positively charged

19

What two types of transporter cause secretion of diuretics into the proximal tubules?

OATs

OCTs

depending on if they're acidic or basic

20

Why aren't diuretics toxic?

Transporters make sure [diuretic]urine > [diuretic]blood

21

Which membranes do transporters have to get diuretics through to secrete them into the proximal tubules?

Capillary membrane

Basolateral membrane

Apical membrane

22

Which transporter moves acidic diuretics across membranes towards the proximal tubule?

OAT

23

Which transporter moves alkaline diuretics across membranes towards the proximal tubule?

OCTs

24

Which other transporter may move acidic diuretics across the apical membrane of tubular cells?

MRP2

multi-drug-resistance protein

25

What effect do loop diuretics have?

How?

Torrential diuresis

Block Na/K/2Cl triple transporter

Medulla's osmolarity doesn't increase because it's not getting Na, K and Cl

So corticomedullary conc. gradient is abolished

So water isn't reabsorbed in Loop of Henle

26

By which route is magnesium and calcium absorbed into the interstitium around the ascending limb?

Why?

Paracellular

Electrochemical gradient - Na+, K+ (but leaks back) and 2 Cl- move into interstitium via triple transporter, so medulla is NEGATIVE

So Mg2+ and Ca2+ are attracted to it

27

The reabsorption of which ions is directly blocked by loop diuretics?

Ca2+, Mg2+

because loop diuretics abolish electrochemical gradient between tubules and medullary interstitium

and these ions aren't reabsorbed anywhere else

28

Apart from Ca2+ and Mg2+, what other ion will patients on loop diuretics be deficient in?

K

more Na+ reabsorption in collecting ducts, so more K+ secretion

look over this

29

Why can loop diuretics be used to treat pulmonary oedema?

Drains fluid pretty much

30

How do loop diuretics enter the proximal tubules?

Transport by OATs

because they're acidic