(LEC) Toxic Response of the Kidney Flashcards
The kidney releases _________ and ______________
Renin, Erythropoietin
Principal role: Excretion of
metabolic wastes
Kidney
(T/F) The kidney metabolizes VIT A into 1,25 dihydroxyvitamin D
False. it metabolizes VITAMIN D3
(T/F) The kidney plays a role on acid-base balance and electrolyte composition
True
(T/F) The kidneys ensure the regulation of extracellular fluid volume
True
Anatomical areas of the kidney (CMP)
- Cortex (90%)
- Medulla (~6-10%),
- Papilla (1-2%)
Functional units of the kidney
NVGT
- Nephron
- Vascular element
- Glomerulus
- Tubular element
A complex, specialized capillary bed composed primarily of endothelial cells.
Glomerulus
Interlobar, arcuate, interlobular arteries and afferent arterioles that supply the glomerulus
Renal artery
(T/F) BOTH afferent and efferent arterioles control glomerular capillary pressure and glomerular plasma flow rate.
True
Carry the blood away from the glomerulus
Afferent arteriole
Deliver the blood to the glomerulus
Efferent arteriole
The glomerulus is a complex, specialized capillary bed composed primarily of __________________ cells.
Endothelial
Three discrete segments of the proximal tubule
CTR 123
S1 (pars convolute)
S2 (transition between pars convolute and pars recta)
S3 (pars recta)
Workhorse of the nephron that reabsorbs 60-80% of solute and water filtered at the glomerulus
Proximal tubule
(T/F) The proximal tubule reabsorbs virtually all the filtered high MW proteins by specific exocytotic protein reabsorption processes.
False. It reabsorbs virtually all the filtered LOW MW proteins by specific ENDOCYTOTIC protein reabsorption processes.
This is characterized by an attenuated and fenestrated cytoplasm & visceral epithelial cells
Renal Vasculature/Glomerulus
Reabsorbs 25% Na and K and 20% of filtered water
Loop of Henle
Iso-osmotic to the renal interstitium (water is freely permeable)
Tubular fluid entering the Thin descending limb
Impermeable to water, and electrolytes are reabsorbed by the active Na+/K+/2Cl- cotransport mechanism
Thin ascending limb
________ distal tubule reabsorbs most of the remaining impermeable to water.
Early distal tubule
(T/F) The late distal tubule, cortical collecting tubule, and medullary collecting duct perform the final regulation and finetuning of urinary volume and composition.
True
Build up of Nitrogenous waste in blood caused by decrease in GFR (AKI)
Azotemia
Abrupt decline in GFR with resulting azotemia
Acute Kidney Injury
A complex disorder that comprises multiple causative factors with clinical manifestations ranging from minimal elevation in serum creatinine to anuric renal failure.
Acute Kidney Injury
Decline in GFR result from?
Prerenal, postrenal, intrarenal factors
Cause of GFR decline
renal vasoconstriction, intravascular volume depletion, insufficient cardiac output
Prerenal factors
Afferent arteriolar constriction so dec. blood flow
Cause of GFR decline
ureteral or bladder obstruction
Postrenal factors
Obstruction inc. tubular pressure = dec. GFR
Cause of GFR decline
glomerulonephritis, tubular cell injury, death and loss resulting in back leak
Intrarenal
Back leak in intracellular space/bloodstream
Mechanisms of chemically-induced acute kidney injury
NSAID, Radiocontrast agents, Cyclosporine, Ampho B, Tacrolimus
Vasoconstriction
Never Run Cats After tacos (NRCAT)
Mechanisms of chemically-induced acute kidney injury
Sulfonamides, Methotrexate, Acyclovir, Triamterene, Ethylene glycol, Protease inhibitors
Crystalluria
Silly Monkeys Are Trying Extra Potions (SMATEP)
Mechanisms of chemically-induced acute kidney injury
Cyclosporine, Mitomycin C, Tacrolimus, Cocaine, Conjugated estrogens, Quinine
Endothelial Injury
Mechanisms of chemically-induced acute kidney injury
Gold, Penicillamine, NSAID
Glomerulopathy
Gold Pigs Nibble (GPN)
Mechanisms of chemically-induced acute kidney injury
Antibiotics, NSAID, Diuretics
Interstitial Nephritis
Anti Naughty Dog (AND)
Mechanisms of chemically-induced acute kidney injury
Aminoglyco, Cisplatin, Vancomycin, Pentamidine, Radioconstrast agents, Heavy metals, Halo-alkane
Tubular Toxicity
Mechanisms of chemically-induced acute kidney injury
Diuretics, ARa, ACEi, Anti-htn
Prerenal
Something to do with htn + diuretics
Nephrotoxic Insult
Path of Uninjured Cells
Compensatory hypertrophy, Cellular adaptation, Cellular proliferation
Nephrotoxic Insult
Path of Injured Cells
Cellular repair, Cell death
Nephrotoxic Insult
_________________> Re-epithelialization > Differentiation
Cellular proliferation
Endpoint after toxic insult
Structural and functional recovery of nephron
Chemicals that induce renal deterioration
Analgesics, Lithium, Cyclosporine (ALC)
Progressive deterioration of renal function may occur with longterm exposure to various chemicals
Chronic Kidney Disease
longterm exposure = chronic
Leads to tubular atrophy and interstitial fibrosis
CKD
(T/F) A nontoxic concentration of a chemical in the plasma may reach toxic concentrations in the kidney and its tubules.
True
The kidneys receive ____% to ____% of resting cardiac output
20% to 25%
NSAID toxicity mechanism
prostaglandin synthesis suppressor → ↓renal blood flow → AKI
ACEi toxicity mechanism
block vasoconstriction → precipitous decline in filtration pressure and AKI
Site selective injury can be attributed to:
- site-specific differences in blood flow
- transport and accumulation of chemicals
- physicochemical properties of the epithelium
- reactivity of cellular/ molecular targets
- balance of bioactivation/ detoxification reactions
- cellular energetics
- regenerative/ repair mechanisms
Initial site of chemical exposure within the nephron
Glomerulus
Glomerular Injury
Impair glomerular ultrafiltration without significant loss of structural integrity and decrease GFR
Drugs
Cyclosporine, Amphotericin B, Gentamicin
Glomerular injury
↓GFR by renal vasoconstriction and ↓glomerular capillary ultrafiltration coefficient (Kf)
Specific Drug
Amphotericin B
Glomerular injury
interacts with anionic sites on the endothelial cells → ↓GFR and Kf
Specific Drug
Gentamicin
Glomerular injury
Renal vasoconstriction and vascular damage, injurious to the glomerular endothelial cell
Specific drug
Cyclosporine
Proximal Tubular Injury
Most common site of toxicant-induced
renal injury
Proximal tubule
Proximal Tubular Injury
(T/F) The proximal tubule has a tight epithelium, favoring the outflow of compounds outside proximal tubular cells
False. The proximal tubule has a leaky epithelium, favoring the flux of compounds into proximal tubular cells
Proximal Tubular Injury
Localized primarily in proximal tubule
Organic anions, cations, low MW proteins and peptides, GSH conjugates, and heavy metals
Loop of Henle / Distal Tubule / Collecting Duct Injury
These drugs induce an ADH resistant polyuria occurs at the level of the medullary thick ascending limb and /or the collecting duct.
Amphotericin B, Cisplatin, Methoxyflurane
Loop of Henle / Distal Tubule / Collecting Duct Injury
Manifestation of functional abnormalities in distal nephron sites
Impaired concentrating ability and/or acidification defects
Papillary injury
Susceptible to the chronic injurious effects of abusive consumption of analgesics
Renal papilla
Papillary injury
Initial target of abusive consumption of analgesics
Medullary interstitial cells > Degenerative changes in capillary > Loops of Henle > Collecting ducts
Site specific biomarkers
Thrombotic microangiopathy
Glomerulus/Kidney
Site specific biomarkers
Collagen IV, Cystatin C, Total protein
Glomerular markers
Site specific biomarkers
Calbindin d28, RPA-1
Collecting duct markers
Site specific biomarkers
NHE3, Osteopontin
Loop of Henle markers
Site specific biomarkers
Clusterin, H-FABP, NGAL, Osteopontin, pi-GST
Distal tubule markers
Specific Nephrotoxicants
Heavy metals
Mercury, Cadmium
Specific Nephrotoxicants
Characterized by proximal tubular necrosis and AKI within 24 to 48 hours after administration.
Mercury
HgCl2
Specific Nephrotoxicants
Induce proximal tubule dysfunction (S1 and S2 segments) and injury that may progress to chronic interstitial nephritis
Cadmium
Specific Nephrotoxicants
Proteinuria, glucosuria, ↑BUN levels
Inc. BUN = Chloroform induced nephrotoxicity
Chloroform
Specific nephrotoxicants
Primary cellular target of chloroform
Proximal tubule
Specific Nephrotoxicants
The products of the reaction are ammonia, pyruvate, and a reactive thiol that is capable of binding covalently to cellular macromolecules, causing cellular damage.
Tetrafluoroethylene
Specific Nephrotoxicants
Penultimate nephrotoxicant (under TFE)
Cysteine S-conjugate
Specific Nephrotoxicants
(T/F) Chloroform poses no primary damage to the glomerulus or distal tubule.
True
Specific Nephrotoxicants
(T/F) Biotransformation of bromobenzene and other halogenated benzenes is critical for their nephrotoxicity.
True
Specific Nephrotoxicants
Metabolizes bromobenzene and conjugates it to glutathione
Hepatic cytochrome P450
It is released it as a form that can cause nephrotoxicity
Specific Nephrotoxicants
1000-fold more potent than bromobenzene
diglutathione conjugate of the hydroquinone
Specific Nephrotoxicants
(T/F) Mycotoxins are products of bacteria and fungi
False. Molds and fungi.
Mycotoxins produce nephrotoxicity.
Specific Nephrotoxicants
↓urine osmolality, GFR and RBF, glycosuria, ↑urinary enzyme exretion
Citrinin nephrotox
Specific Nephrotoxicants
- Found on corn and corn products
- Nephrotoxicity in rats and rabbits (↑ urine volume, ↓osmolality, ↑ low and high MW proteins)
Fumonisins B1 and B2
Specific Nephrotoxicants
Aristolachia and I genera
Aristolochic acids and aristolactams
(tubular dysfunction, proteinuria, interstitial fibrosis)
Specific Nephrotoxicants
Upon a large dose of (answer), AKI may occur within hours; but reversible on withdrawal
Chronic consumption >3 years – irreversible nephrotoxicity (Analge
NSAIDs
such as Aspirin, Ibuprofen, Naproxen, Indomethacin,
celecoxib
Specific Nephrotoxicants
Proximal tubular necrosis with increases in BUN and plasma creatinine, ↓ GFR, and clearance of para-aminohippurate
Acetaminophen
Specific Nephrotoxicants
Characterized by non oliguric renal failure with ↓ GFR, ↑serum creatinine, and proteinuria
Aminoglycosides
(T/F) The process that concentrates urine also serves to concentrate potential toxicants in the tubular fluid.
True
(T/F) Toxicants may also cause mitochondrial dysfunction via compromised respiration and ATP prod; leading to apoptosis or necrosis
True