Cholesterol depletion affects the Ca2+ influx but not the Ca2+ pump in human erythrocytes.
Control and cholesterol-depleted human erythrocytes were loaded with permeant Ca2+ chelators (Benz2-AM or Quin2-AM) in order to increase their exchangeable Ca2+ pool and to measure both Ca2+ fluxes and [Ca]i (free cytoplasmic calcium concentration). The fluxes were independent of the concentration and of the nature of the intracellular chelator. The ATP content was not decreased by more than 50% under our experimental conditions. Cholesterol depletion (up to 28%) induced a decrease in both Ca2+ fluxes and [Ca]i which was proportional to the extent of the depletion. It is shown that cholesterol depletion primarily altered the properties of the system responsible for Ca2+ entry causing a diminution of the [Ca]i. This, in turn, induced a diminution of the activity of the Ca2+ pump without affecting the properties of this pump.
D000255:Adenosine Triphosphate / Q000097:blood; D000634:Aminoquinolines; D002118:Calcium / Q000097:blood*; D002132:Calcium Radioisotopes; D002614:Chelating Agents; D002784:Cholesterol / Q000097:blood / Q000502:physiology*; D004912:Erythrocytes / Q000378:metabolism*; D005456:Fluorescent Dyes; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D007700:Kinetics; D009930:Organic Chemicals
D000634:Aminoquinolines; C041685:Benz2; D002132:Calcium Radioisotopes; D002614:Chelating Agents; D005456:Fluorescent Dyes; D007473:Ion Channels; D009930:Organic Chemicals; C035738:Quin2-acetoxymethyl ester; D000255:Adenosine Triphosphate; D002784:Cholesterol; D002118:Calcium