A high concentration of pyruvate is essential for survival and DNA synthesis in primary cultures of adult rat hepatocytes in a serum-free medium

When adult rat hepatocytes were cultured in a serum-containing medium supplemented with glucagon and insulin, DNA synthesis was induced regardless of pyruvate concentration in the culture medium. In contrast, in a serum-free medium, degeneration of hepatocytes was observed at pyruvate concentrations below 5 mM. However, hepatocytes survived and DNA synthesis was induced in a serum-free medium when pyruvate at higher concentrations (more than 5 mM) was present. DNA synthesis in a serum-free medium was dependent on pyruvate concentration and increased linearly up to 40 mM. Addition of glucose or fructose (20 mM each) to a low pyruvate medium (1 mM) did not prevent hepatocytes from degeneration. These results indicate that a high concentration of pyruvate could be substituted for serum in cultivation of hepatocytes. From these observations, we propose that pyruvate is involved in one of the key cellular processes of the induction of DNA synthesis.