Use of a new citrulline incorporation assay to investigate inhibition of intercellular communication by 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane in human fibroblasts

A citrulline incorporation assay has been developed to measure intercellular communication between argininosuccinate synthetase-deficient and argininosuccinate lyase-deficient human fibroblasts (J. S. Davidson, I. M. Baumgarten, and E. H. Harley, Exp. Cell Res., 150: 367-378, 1984). This method was used to investigate the effects of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) on intercellular junctional communication. DDT at a concentration of 20 micrograms/ml inhibited metabolic cooperation by 90 to 98%. This inhibition was of rapid onset and was rapidly reversed by washing the cells. Inhibition of metabolic cooperation by DDT was not dependent on the presence of extracellular free calcium, indicating that DDT does not act by increasing net calcium influx into cells. This system should prove useful in elucidating the relationship between tumor promotion and intercellular communication.