The influence of medium composition on the maintenance of cytochrome P-450, glutathione content and urea synthesis: a comparison of rat and sheep primary hepatocyte cultures.

Rat and sheep primary hepatocytes have been cultured in four different medium formulations: Williams' E, Chee's, Medium 199 and Modified Earle's. The total cytochrome P450 content, intracellular concentration of reduced glutathione, rate of urea synthesis and total protein content of cultures of cells from both species in each medium have been determined. Modified Earle's and Chee's medium proved to be the most favourable formulations for the culture of rat hepatocytes. After 48 h, cells cultured in Modified Earle's had significantly more cytochrome P450 and a significantly greater rate of urea synthesis than cells in any other medium. After 6 days in culture the difference in cytochrome P450 levels between rat hepatocytes in Chee's medium and those in Modified Earle's medium was abrogated. The difference in the rate of urea synthesis between rat hepatocytes cultured in each of these two media was shown to be more dependent on the medium in which the cells were maintained during the period of urea synthesis measurement than on the medium in which the cells had been previously cultured. Sheep hepatocytes cultured in Chee's medium ruptured and died within 24 h. Apart from this, sheep cells were less sensitive to changes in medium formulation than were rat hepatocytes. The initial plating efficiency was lower in sheep cells. Total cytochrome P450 content was the most discriminatory of the four parameters for evaluating the status of rat hepatocyte cultures. However, urea synthesis may be the most useful parameter for assessment of hepatocyte function in hybrid liver devices such as bioartificial liver support systems where access to the cells during operation of the device is restricted.