DIURETICS (INTRO TO KIDNEY PHYSIO)

DIURETICS

• Drugs that increase urine volume by inhibiting the reabsorption of certain solutes (Na+, K+, Cl-) and/or water in the tubular system of the kidneys.

5 CLASSES OF DIURETICS

• Carbonic Anhydrase Inhibitors

• Loop Diuretics

• Thiazide Diuretics

• Potassium-sparing diuretics

• Osmotic Diuretics

nephron

• functional unit of the kidney.

nephron/ kidney consists of

• Renal Corpuscle

  • Bowman’s Capsule

  • Glomerulus

• Proximal Convoluted Tubule

• Loop of Henle

  • Descending Limb

  • Ascending Limb

• Distal Convoluted Tubule

PROXIMAL CONVOLUTED TUBULES (PCTs)

• Carries out isosmotic reabsorption of amino acids, glucose, and numerous ions

• Major site for NaCl and NaHCO₃ reabsorption

• Na+ is separately absorbed from the lumen in exchange for H+ ions via NHE3 and is transported to the blood using the Na+/K+ ATPase (Na/K pump)

• Weak acid absorption occurs at the early straight segment (S1) of PCT. 

• Weak bases are absorbed inthe S1 and middle segment (S2).

• Glucose is reabsorbed in PCT through SGLT2

PROXIMAL CONVOLUTED TUBULES (PCTs)

• Carries out isosmotic reabsorption of

amino acids, glucose, and numerous ions

PROXIMAL CONVOLUTED TUBULES (PCTs)

major site for __

 NaCl and NaHCO₃ reabsorption

PROXIMAL CONVOLUTED TUBULES (PCTs)

Na+ is separately absorbed from the lumen in exchange for H+ ions via

NHE3 and is transported to the blood using the Na+/K+ ATPase (Na/K pump)

PROXIMAL CONVOLUTED TUBULES (PCTs)

carbonic anhydrase

• enzyme required for the HCO3- reabsorption process in the brush border and in the cytoplasm

Weak acid absorption occurs at the

early straight segment (S1) of PCT.

Weak bases are absorbed in the

S1 and middle segment (S2). 

Glucose is reabsorbed in PCT through

SGLT2

THICK ASCENDING LIMB OF THE LOOP OF HENLE

• Pumps Na+/K+/Cl- out of the lumen and into the kidney interstitium via Na+/K+/Cl- carrier (NKCC2 or NK2Cl).

• Thick Ascending Limb is the major site for Ca+2/Mg+2 reabsorption which then creates a (+)- potential that is the driving force for the cation reabsorption.

THICK ASCENDING LIMB OF THE LOOP OF HENLE

• Pumps Na+/K+/Cl- out of the lumen and into the kidney interstitium via

• Na+/K+/Cl- carrier (NKCC2 or NK2Cl).

THICK ASCENDING LIMB OF THE LOOP OF HENLE

Thick Ascending Limb is the major site for __

Ca+2/Mg+2 reabsorption which then creates a (+)- potential that is the driving force for the cation reabsorption

DISTAL CONVOLUTED TUBULES (DCT)

• Actively pumps Na+/Cl- out of the lumen of the nephron via Na+/Cl- carrier (NCC).

•  Ca+2 is also reabsorbed at this segment under the regulation of the parathyroid hormone (PTH).

DISTAL CONVOLUTED TUBULES (DCT)

• Actively pumps Na+/Cl- out of the lumen of the nephron via

Na+/Cl- carrier (NCC).

DISTAL CONVOLUTED TUBULES (DCT)

•  Ca+2 is also reabsorbed at this segment

under the regulation of the parathyroid hormone (PTH).

CORTICAL COLLECTING TUBULES (CCT)

• The last segment of Na+ reabsorption and is regulated by aldosterone.

• Reabsorption is made via the epithelial sodium channel (ENaC). This absorption is accompanied by K+/H+ excretion.

• Primary site for urine acidification

CORTICAL COLLECTING TUBULES (CCT)

• The last segment of Na+ reabsorption and is regulated by

aldosterone.

CORTICAL COLLECTING TUBULES (CCT)

• Reabsorption is made via the __ This absorption is accompanied by K+/H+ excretion.

epithelial sodium channel (ENaC).

CORTICAL COLLECTING TUBULES (CCT)

• Primary site for

urine acidification

ADH ON COLLECTING TUBULES

• activates V2 receptors (G-protein coupled) which stimulates levels of cAMP.

• cAMP activates protein kinase A (PKA) that activates in turn aquaphorin-2 (AQP2) in the apical membrane of the collecting ducts’ cells.