Increased proximal tubular cholesterol content: implications for cell injury and "acquired cytoresistance"

Kidney Int. 1999 Nov;56(5):1788-97. doi: 10.1046/j.1523-1755.1999.00745.x.


Background: Acute renal failure (ARF) leads to secondary adaptive changes that serve to protect proximal tubules from subsequent ischemic or toxic damage [so-called "acquired cytoresistance" (CR)]. A characteristic of CR is increased plasma membrane resistance to attack. Therefore, this study sought to identify potential changes in plasma membrane lipid composition in CR tubules/renal cortex and, if present, to test whether they might mechanistically contribute to the CR state.

Methods: Renal cortices/isolated tubules were obtained from CR mouse kidneys (18-hr postinduction of ischemia reperfusion, myoglobinuria, or ureteral obstruction). Their plasma membrane phospholipid/cholesterol profiles were compared with those observed in either control tissues or tissues obtained one to two hours post-renal damage (that is, prior to emergence of CR).

Results: Either no changes or inconsistent changes in phospholipid profiles were observed in CR tissues. Conversely, CR (vs. control) tissues demonstrated a consistent 25 to 50% increase in membrane cholesterol content. To ascertain whether cholesterol impacts tubule susceptibility to injury, its levels were reduced in proximal tubule (HK-2) cells with either (a) mevastatin, (b) a cholesterol "stripping" agent, (c) cholesterol oxidase, or (d) cholesterol esterase. Then cell susceptibility to injury [adenosine 5'-triphosphate (ATP) depletion; Fe-mediated oxidant stress] was assessed. In each instance, cholesterol reductions dramatically sensitized to superimposed injury (for example, a 2 to 3 times increase in the % of lactate dehydrogenase release). When cholesterol levels were restored to normal in CR tubules (with a "stripping" agent), an increased tubule susceptibility to injury resulted. Because cholesterol decreases membrane fluidity, the impact of a membrane-fluidizing agent (A2C) on cell injury was assessed. A2C dramatically sensitized HK-2 cells to superimposed attack.

Conclusions: ARF leads to an up-regulation of proximal tubule cholesterol content. The latter may then contribute to acquired CR, possibly by stabilizing the plasma membrane via its antifluidizing effect.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acute Kidney Injury / metabolism
  • Animals
  • Cholesterol / analysis
  • Cholesterol / physiology*
  • Cholesterol Oxidase / pharmacology
  • Cyclodextrins / pharmacology
  • Cytoprotection*
  • Kidney Cortex / chemistry
  • Kidney Tubules, Proximal / chemistry
  • Kidney Tubules, Proximal / pathology*
  • Lovastatin / analogs & derivatives
  • Lovastatin / pharmacology
  • Male
  • Membrane Fluidity
  • Mice
  • Phospholipids / analysis
  • Sterol Esterase / pharmacology
  • beta-Cyclodextrins*


  • Cyclodextrins
  • Phospholipids
  • beta-Cyclodextrins
  • methyl-beta-cyclodextrin
  • mevastatin
  • Cholesterol
  • Lovastatin
  • Cholesterol Oxidase
  • Sterol Esterase