Kidney Pharm Flashcards
(31 cards)
What are the mechanisms of reabsorption in the PCT?
NaHCO3, NaCl, glucose, amino acids, and other organic solutes are reabsorbed via transport systems.
K+ follows it’s gradient in the paracellular pathway
NaHCO3 and NaCl are most relevent toward diuretic action
Which diuretic group works primarily in the PCT?
CA inhibitors
Block the reabsorption of HCO3
Where are organic acid secretory systems located?
The meddle part of the straight part of the proximal tubule.
What is the function of the thick ascending limb “loop diurectics”?
They block the Na2ClK symporter that reabsorbs only solute and dilutes the luminal fluid. When K+ is reabsorbed it creates a high concentration in the cell resulting in back leak into the lumen. This increases the + ion concentration and provides a gradient for the paracellular reabsorption of Mg2+ and Ca2+.
What loss of ions does loop diuretic cause?
K+, Na+, Mg2+, Ca2+, Cl-
What diuretics affect the DCT?
Thiazide diuretics block the NCC symporter responsible for reabsorption of Na and Cl-.
Do thiazide diuretics affect Ca2+ reabsorption?
No, Ca2+ in the DCT is accomplished via a channel that is sensitive to the gradient created by the Ca2+/Na+ exchanger on the interstitial side. This is stimulated by PTH
What is the site where all adjustments to K+ is regulated?
The collecting tubule system
What is the function of the principal cells of the distal tubule?
They are the major site of Na+, K+, and H20 transport
What is the function of the intercalated cells of the distal tubule?
H+, and HCO3 secretion
How does transport in the principal cells work?
Na+ and K+ have seperate channels on luminal membrane
More Na+ enters than K+ is secreted creating 50-70mV negative change in lumen
Negative charge drives paracellular Cl- reabsorption and draws K+ out of the cell
Through what mechanism does aldosterone act?
It increases luminal expression of ENaC and increases action of Na+/K+ transporters,
Through gene transcription it causes an increase in transepithelial negative potential resulting in more Na+ uptake and more K+ excretion.
What cells does ADH affect?
Principal cells to increase expression of AQP2 and UT1 (in the medulla)
What is the effect of prostaglandins in the kidney?
They block the reabsorption of Na+ and the TAL and block the reabsorption of water at the CD.
Blockade of prostaglandins with NSAIDS can decrease the efficacy of loop diuretics because of the necessary aciton of PGE2
What are the uses of CA inhibitor diuretics?
Glaucoma (decreased fluid formation)
Unrinary Alkalization (To prevent stone formation in cystinuria)
Metabolic Alkalosis
Acute Mountain Sickness (to excrete excess bicarb)
What are the toxicities of CA inhibitors?
Hyperchloremic Metabolic Acidosis (until stopped)
Renal Calculi (Ca2+ insoluble in alkalotic urine)
Renal K+ wasting
Drowsiness
Parasthesias
When are CAs contraindicated?
Cirrhosis
What are clinically important indications for loop diuretics?
Acute pulmonary edema Acute hypercalcemia (give with saline) Hyperkalemia Acute Renal Failure Anion Overdose
What are the toxicities of loop diuretics?
Hypokalemic Metabolic Acidosis (increased Na in CD)
Ototoxicity
Hyperuricemia (hypovolemia enhances Uric Acid reab)
Hypomagnesemia (no electrical gap to drive reab)
What are the major clinical indications for thiazide diuretics?
Hypertension
Heart failure
nephrolithiasis due to hypercalciuria
Nephrogenic diabetes insipidus
What are the toxicities of thiazide diuretics?
Hypokalemic metabolic acidosis Impaired carbohydrate tolerance Hyperlipidemia Hyponatremia Allergic reactions
How do spironolactone and eplerenone cause diuresis?
Blocking the effects of aldosteron via competitive inhibition
How does amilioride exhibit its effect?
Blocking ENaC
What are the toxicities of K+ sparing diuretics?
Hyperkalemia Hyperchloremic Metabolic Acidosis Gynecomastia Acute Renal Failure Kidney Stones
