BIOL 2P93 Lecture Notes - Proximal Tubule, Furosemide, Blood Pressure
23 views1 pages
4 Feb 2013
School
Department
Course
Professor
Control of ECF & Composition V
Diuretics
I. Intro
a. Terms
i. Diuretic—an agent that increases urine flow rate by inhibiting
reabsorption of solutes & H2O
ii. Edema—increase in fluid in interstitial space
iii. Diuretic Rebound—phenomenon that occurs when one stops taking
diuretics and see even more accumulation of ISF than before diuretic use
(due to compensatory mechanism)
b. Heart Failure—as heart begins to fail → blood pools in veins → baroreceptors
sense ↓ venous return (↓ fluid) → kidneys retain more fluid → ↑ venous pressure
& congestion → buildup of ISF
* diuretics => ↑ fluid excretion!
II. Classes of Diuretics
a. Hydrogen Transport Inhibitors (Carbonic Anahydrase Inhibitors)
i. Work in proximal tubule
ii. Inhibit NaHCO3 and H2O reabsorption
b. Loop Diuretics (TAL transport inhibitors)—Furosomide & Lasix
i. Most commonly used diuretics!!
ii. Block Na transport across TAL membrane => inhibit reabsorption
iii. K+ wasting diuretics b/c ↑ fluid flow in CCD => ↑ K+ secretion
1. taking K+ supplements is important!!!!
c. Distal Tubule Diuretics—thiazides
i. Block Na reabsorption in DCT
ii. Also K+ wasting by same mechanism as loop diuretics
d. Collecting Duct Diuretics—Amiloride
i. Inhibit Na+ transport in collecting tubule
ii. K+ sparing by indirectly inhibiting K+ secretion
e. Osmotic Diuretics—Mannitol
i. Freely filtered by glomerulus but not reabsorbed => increase osmolality of
collecting duct fluid => reduced H2O reabsorption