• on lumen side
  • Na/H antiporter (Na reabsorbed, H into tubule)
  • Cl/organic base antiporter (Cl reabsorbed)
• on interstitial/blood side
  • Na/K pump
  • HCO₃ channel
    • for each HCO₃ reabsorbed, there is one hydrogen secreted into lumen
  • symporters (reabsorbed
    • Na/glucose
    • Na/phosphate
    • Na/AA

• acetazolamide (CA inh.)
• chlorothiazide (thiazide diuretic)
• furosemide (loop diuretic)
• penecilin
• probenecid
• salicylate (aspirin)
• HTZ (thiazide diuretic)
• bumetanide

• atropine (muscarinic antagonist)
• isoproterenol
• cimetidine
• morphine
• quinine
• amiloride
• procainamide

• sodium is reabsorbed with bicarbonate in the early PCT
• in the lat PCT, chlorine is very concentrate
• Cl and Na are reabsorbed at this point via paracellular pathway
• water will follow NaCl due to osmosis

• drugs that our bound to protein cannot enter nephron lumen UNLESS these transporters secrete them into the lumen
• they have a finite rate of secretion
  • so two drugs may have to compete for the same transporters
  • this alters rate of elimination/action

• lumen side
  • NKCC channel (all reabsorbed)
  • K channel (secreted)
    • causes positive potential drives movement of Mg and Ca into blood
• interstitium/blood side
  • Na/K pump
  • K/Cl cotransport

Called diluting segment due to its impermeability to water

1. renal artery branch into interlobar A.'s
2. interlobar into arcuate A's
3. arcuate A's into interlobular A's
4. interlobular into afferent arteriole
5. afferent arteriole into glomerular capillaries
6. glomerullar capillaries into efferent arteriole
7. two options
   1. outer cortex: efferent arteriole into peritubular capillaries
   2. inner cortex: efferent arteriole into vasa recta

• cortex (decreases as we go inward to medulla)

• in conjunction with the early DCT

• 180 L if filtrate produced a day, but only 1.5 L of urine/day
• this means most of the filtrate is reabsorbed
  • ex: AA, urea, ions, glucose

• 3Na/2K ATP pump at the basolateral membrane of tubule cells (establishes ionic gradient)

• can be transcellular or paracellular
• follows solute absorption
• water absorption can also resulte in "solvent drag"

• many drugs are bound to a protein, so they cannot enter the lumen via filtration
• only way protein bound is via secretion

• at this point, Cl becomes concentrated
• reabsorbed along with sodium via paracellular pathway with water following

• water permeable but impermeable to NaCl
  • water is reabsorbed
  • NaCl concentrated in the tubule

• Na/Cl cotransporter (into cell) on luminal side
• Ca channel (into cell) on luminal side
• Na/K pump on basolateral side
• Na/Ca antiport (Na in, Ca out) on basolateral side (driving force for calcium reabsorption)

• principle cells
• intercalated cells

• sodium channel (sodium into cell) on lumen side
• potassium channel (potassium into lumen) on lumen side
• V2 channel (water into cell) on lumen side
• Na/K pump on basolateral side

• H/ATPase pump (H into lumen) on luminal side
• K/H pump (H into lumen, K into cell) on luminal side
• K channel (K out) on basolateral side
• HCO₃/Cl antiport (HCO₃ into blood, Cl into cell) on basolateral side

• increase in ECF volume
• no increase in osmolality of any compartment
• no change in volume of ICF

• decreased osmolarity in both ECF, ICF
• increased volume in both ECF and ICF

• ECF volume increase
• ICF volume decrease
• increase osmolality in both compartments

• Na/2Cl/K channel in TAL
• urea reabsorbed from collecting duct along with water

• via the vasa recta
• as we go more inside the medulla of the kidney nephron, we see recirculation of solutes
  • at descending arm, water out and solutes in
  • at ascending arm, solutes out, water in
• this leads to recirculation

1. body senses increase in plasma osmolality (senses at about 280 mOsm/kg H₂O)
   • could also fire to significant decreases in volume
2. stimulation of osmoreceptors in the supraoptic and paraventricular areas of hypothalamus
3. ADH produced by hypothalamus and released from post. pit.
4. ADH bind to principle cell R's in CD
5. upgregulates adenylate cyclase, leading to increase cAMP
6. activate PKA, leading to phosphorylation of vesicles containing V₂ channels
7. V₂ channel vesicles fuse with apical cell membrane
8. increase water and urea reabsorption
   • decrease urine volume
   • increase urine osmolality

1. NaCl transported into macula densa cells via Na/K/Cl
2. when it is high
   • inhibit COX2 enzyme from making PG
3. when it is low
   • COX2 produce PG's
   • via G_s mechanism, stimulate granular cells to release renin

Also, when ATP hydrolyzed, can produce ADO and inhibit cAMP, thereby inhibit renin release.

• decreased effective circulating volume could be sensed by baroR leading to increased sympathetic stimulation of granular cells via beta 1
• decrease renal perfusion pressure in afferent arterioles

• intrarenal and systemic vasoconstriction
• increased PCT sodium reabsorption
• increased Ald, leading to increased sodium reabsorption, increased potassium and hydrogen excretion
• increased ADH, leading to increased water reabsorption

• mechanism of production (serves as counter regulatory pathway for production of Ang II)
  • produced from Ang II via ACE2
• effect on body
  • produces vasodil.
  • inhibits prolif. of vascular smooth muscle
• clinical app.- ACE inhibitors usually dont inhibit ACE2, but rather increase circulating levels of Ang 1-7

• increase plasma potasssium
• increase levels of Ang II

• principle cells
  • increase active Na channels on lumen side
  • increase Na/K pump activity
  • increase K channel activity
  • increase Na/H antiport activity
• intercalated cells
  • increase H/ATPase activity

Happens over a period of hours to days. Remember, its a steroid hormone that translocates to the nucleas via activated receptor complex

• loop and thiazide diuretics
• vomiting
• hyperAld

• diarrhea
• DM
• CA inh.
• K sparring diuretics
• renal failure