Renal failure results when approximately three fourths of the
nephrons of both kidneys cease to function. Acute renal failure
(ARF) results from an abrupt decline in renal function, and is
usually caused by an ischemic or toxic insult to the kidneys.
Ischemic or toxicant-induced injury most frequently results in
damage to the metabolically active proximal tubular and thick
ascending loop of Henle's epithelial cells, causing impaired
regulation of water and solute balance. Nephrotoxicants
interfere with essential tubular cell functions and cause
cellular injury, swelling, and death. Renal ischemia causes
cellular hypoxia and substrate insufficiency, which leads to ATP
depletion and cellular swelling and death. Vasoconstriction
secondary to toxic or ischemic tubular epithelial injury further
decreases glomerular filtration. It is important to note that
tubular lesions and dysfunction caused by toxic and ischemic
insults may be reversible. In contrast, nephron damage
associated with chronic renal failure (CRF) i