Calcium depletion prevents the anoxic death of cultured hepatocytes by
inhibiting the mitochondrial permeability transition.
Pastorino, John G., Jack W. Snyder, Jan B. Hoek, and John L. Farber.
Department of Pathology, Thomas Jefferson University, Philadelphia, PA 19107
APStracts 2:0021C, 1995.
Removal of Ca2+ ions from the culture medium or treatment with the
intracellular Ca2+ chelator 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 nor 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). Calcium depletion by either means prevented
the MPT measured in intact cells made anoxic or treated with rotenone. In
isolated mitochondria de-energized by rotenone, BAPTA-AM prevented the MPT
induced by palmitoyl CoA. By contrast, in isolated mitochondria de-energized
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 calcium ions 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 calcium.
Received 15 April 1994; accepted in final form 27 September 1994
APS Manuscript Number C191-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1994 The American Physiological Society.
Published in APStracts on 27 February 1995.