Effects of Ca2+ deregulation on mitochondrial membrane potential and cell viability in nucleated cells following lytic complement attack

Cell Calcium. 1994 Mar;15(3):217-27. doi: 10.1016/0143-4160(94)90061-2.


We have previously shown [Papadimitriou JC. Ramm LE. Drachenberg CB. Trump BF. Shin ML. (1991) J. Immunol., 147, 212-217] that formation of lytic C5b-9 channels on Ehrlich ascites tumor cells induced rapid depletion of adenine nucleotides associated with prelytic leakage preceding cell death. Extracellular Ca2+ concentration ([Ca2+]e) reduction by chelation markedly delayed the onset of cell death, although the adenine nucleotide leakage was enhanced. In the present study, we examined the temporal relationships between ionized cytosolic Ca2+ ([Ca2+]i), mitochondrial membrane potential (delta psi m) and cell death in individual cells by digital imaging fluorescence microscopy (DIFM), during the earliest phase of C5b-9 attack. The results showed an immediate, > 20-fold rise in [Ca2+]i, rapidly followed by dissipation of delta psi m and subsequent acute cell death. These events were markedly delayed by chelation of Ca2+e, but not by nominally Ca2+ free medium. Differing from previous reports indicating propidium iodide labeling of viable cells bearing C5b-9 channels, with DIFM we observed nuclear fluorescence with that marker only in association with cell death. These findings indicate that Ca2+ influx through lytic C5b-9 channels is responsible for the massive increase in [Ca2+]i, as well as for the rapid loss of delta psi m, followed by acute cell death. When this [Ca2+]i increase is prevented, the cell death is probably related to metabolic depletion.

Publication types

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

MeSH terms

  • Adenine Nucleotides / metabolism
  • Animals
  • Calcium / metabolism*
  • Cell Death / physiology*
  • Complement Activation / physiology*
  • Complement Membrane Attack Complex / physiology*
  • Image Processing, Computer-Assisted
  • Intracellular Membranes / physiology
  • Membrane Potentials / physiology
  • Mice
  • Microscopy, Fluorescence / instrumentation
  • Microscopy, Fluorescence / methods
  • Mitochondria / physiology*
  • Tumor Cells, Cultured


  • Adenine Nucleotides
  • Complement Membrane Attack Complex
  • Calcium