Ca2+ depletion prevents anoxic death of hepatocytes by inhibiting mitochondrial permeability transition.
Removal of Ca2+ from the culture medium or treatment with the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM) prevented the killing of rat hepatocytes by anoxia and rotenone, but not by cyanide. Neither manipulation prevented the loss of the mitochondrial membrane potential or the depletion of ATP. A mitochondrial permeability transition (MPT) was demonstrated in digitonin-permeabilized hepatocytes as an increased [3H]sucrose-accessible space sensitive to cyclosporin A (CyA). Ca2+ depletion by either means prevented the MPT measured in intact cells made anoxic or treated with rotenone. In isolated mitochondria deenergized by rotenone, BAPTA-AM prevented the MPT induced by palmitoyl CoA. By contrast, in isolated mitochondria deenergized by cyanide, BAPTA-AM alone did not prevent the MPT. Rather, BAPTA-AM plus CyA were required. Similarly, the killing of cultured hepatocytes by cyanide was prevented by BAPTA-AM plus CyA, but not by either agent alone. The MPT in intact cells treated with cyanide was also prevented by BAPTA-AM plus CyA. These data define a specific requirement for Ca2+ in the killing of hepatocytes that follows the inhibition of electron transport. A model is presented in which the MPT depends on factors that modulate the sensitivity of the permeability transition to the matrix concentration of Ca2+.
Pastorino
J G
JG
Department of Pathology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Snyder
J W
JW
Hoek
J B
JB
Farber
J L
JL
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000008:administration & dosage* / Q000502:physiology; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D016572:Cyclosporine / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D007425:Intracellular Membranes / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials; D008930:Mitochondria, Liver / Q000502:physiology*; D010171:Palmitoyl Coenzyme A / Q000494:pharmacology; D010539:Permeability / Q000187:drug effects; D011190:Potassium Cyanide / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012402:Rotenone / Q000494:pharmacology
D012402:Rotenone; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D010171:Palmitoyl Coenzyme A; D004533:Egtazic Acid; D016572:Cyclosporine; D000255:Adenosine Triphosphate; D011190:Potassium Cyanide; D002118:Calcium