Sriramula Flashcards
Major sites of Sodium Reabsorption
- Proximal Tubule
- 65-70%
- Ascending limb of loop of Henle
- 20-25%
- Distal Tubule
- 5%
- Collecting duct
- 1-5%
- Where sodium goes, water goes
- Less than 1% of the filtered sodium load is excreted per day
Na+
- Kidneys always want to preserve at the expense of other electrolytes
- even K+
- Water follows
- <1% of filtered sodium load exreted per day
What controls renal function
- Renin Angiotensin Aldosterone System
- Renal Nerves/catecholamines
- Renal pressure gradient
- perfusion pressure
- Interstitial pressure
- Vasopressin (ADH)
- Autocoids
- prostaglandins
- Nitric Oxide
- Bradykinin
What is the function of the kidneys
- Fluid and electrolyte homeostasis
- BP control
- Detoxification
What electrolyte is preferentially absorbed by the kidneys?
Sodium at the expense of other electrolyes
even K+
What is the role of the afferent and efferent arteriole
- Differential resistance buiilt in these 2 vascular beds
- blood will be forced to stay in the capsule
- glomerular filtration
- changes in GFR=constriction/dilation of afferent/efferent
What regulate afferent and efferent arteirole tone
x
Why is renin important with renal artery stenosis
- Upregulation of intra-renal renin-angiotensin system maintains GFR in renal artery stenosis patients
- vasoconstricts efferent arterioles
What drugs would lead to renal failure with renal arter stenosis
- ACEIs or ARBs leads to kidney failure.
Diuretics
- Inhibit electrolyte reabsorption in the kidney
- increase rate of urine flow
What are the primary and secondary effects of diuretics
- Primary
- increase solute excretion
- mainly Na+
- increase solute excretion
- Secondary effect
- increase urine flow
- response to the osmotic force of solutes within the renal tubule lumen
- increase urine flow
Different types of Diuretics and major site of action
Epithelial Transporters
- Channels
- Na, K, Cl
- Antiporter/Countertransport
- Na-K ATPase
- Na-H Exchanger
- Sympoter/Cotransport
- Na-Cl
- Na-K-2Cl
Osmotic DIuretics
- Prototype=Mannitol
- no molecular target
- interfer directly with osmosis
- Major site of action=Proximal tubule
Osmotic Diuretic Characteristics
- Free Glomerular Filtration
- Limited or no tubular reabsorption
- Pharmacologically inert
- minor side effects/DDI
What is the MOA of mannitol
- Water moves across the membrane from low osmolarity (dilute side) to higher osmoloarity (Concentrated side)
- Mannitol:
- Loss of water
- Reduced intracellular volume
- Hypernatremic risk
How does bicarbonate ion regulate Sodium Absorption
- Na+-H+ exchanger on luminal border allows Na+ to enter the cell in exchange for H+ ion.
- Next reabsorbed Na+ is pumped out of the cell by Na+-K+-ATPase, whereas, secreted H ion combines with luminal bicarbonate to form carbonic acid.
- This carbonic acid is dissociated by Carbonic Anhydrase enzyme into water and CO2. CO2 diffuses into the cell and is rehydrated to form carbonic acid. Because the concentration of cellular H+ ion is low, carbonic acid dissociates into H+ and bicarbonate.
- Thus the constant supply of H+ is furnished for countertransport of Na+ and absorption of bicarbonate.
Acetozolamide: MOA
- As a result:
- bicarbonate gets retained in the lumen
- No H+ ion is produced for NHE
- results in inhibition of Na+ absorption
illustrate the high ceiling effect of loop diuretics
- high ceiling-greater effect than other diuretics
What is the MOA of loop diuretics
- F=Furosemide
- binds to symporter
- loss of potassium
what are the Extra-renal effects contribute to the diuretic activity and beneficial cardiac effects of loop diuretics
Adverse Effects of Loop Diuretics
