Phalloidin depletes the mitochondrial Ca2+ compartment of hepatocytes

In 3 h of incubation, primary cultures of rat hepatocytes attach to the substratum and exchange about 2.2 nmol 45Ca2+ per mg protein. In the presence of 1 microM phalloidin, the exchanged amount of 45Ca2+ was found to be decreased by about 30%. Using the uncoupling agent FCCP and the ionophore A23187 for further characterisation we determined that the 45Ca2+ deficit caused by phalloidin occurs in the FCCP-sensitive compartment, i.e., the mitochondria.