A co-cultivation system consisting of primary chick embryo hepatocytes and V79 Chinese hamster cells as a model for metabolic cooperation studies.

In this study the role of metabolic cooperation was investigated in a co-cultivation system consisting of primary chick embryo hepatocytes and V79 Chinese hamster cells. A morphological study showed that, in addition to the gap junctions formed between homologous cells, gap junctions were formed also between the primary chick embryo hepatocytes and the V79 Chinese hamster cells. The number of gap junctions present in this system decreased in the following order: hep.-hep., V79-V79, hep.-V79. Under control conditions this number was constant during a co-cultivation period of 48 h. The heterologous gap junctions allowed the passage of 3H-labelled hypoxanthine. Addition of 12-O-tetradecanoylphorbol-13-acetate inhibited this transfer in a dose-related way. Electron microscopical studies with sectioned material showed that inhibition of transfer was paralleled by the disappearance of all gap junctions. There was a remarkable difference between the response time of the different types of gap junctions. Those formed between V79 cells had disappeared after 20 min, whereas those formed between hepatocytes had disappeared after 12 h. The heterologous gap junctions behaved more or less like those between hepatocytes. After exposure times longer than 7 h the transfer of [3H] hypoxanthine was partly restored and morphologically the gap junctions reappeared. When the V79 cells were pretreated with mitomycin C no recovery of intercellular communication was observed, indicating that the adaptation phenomenon is related to the mitotic index of the cells. Dimethylbenzanthracene inhibited the transfer of labelled nucleotides and may be the first example of an indirectly acting inhibitor of intercellular communication.