Factors affecting the lactate dehydrogenase isoenzyme pattern of cultured kidney-cortex cells.

1. The lactate dehydrogenase isoenzyme pattern of cultured calf kidney-cortex cells was correlated to growth phase, changes in oxygen supply, mean generation time and changes in nutritional supply. 2. During culture of free cells and intact explants the lactate dehydrogenase isoenzyme pattern changed towards a dominance of isoenzymes containing the M subunit. 3. Of the shift in monomer proportion, 58% occurred during the lag phase and 42% during the initial part of the exponential growth phase. During the stationary phase the shift in monomer proportion reversed slightly. It was possible to relate the observed shift in monomer proportion to the glycolytic rate. 4. Factors that depressed glycolysis decreased the shift in monomer proportion. Oxygen was found to limit the decrease in the H subunit/M subunit ratio caused by anaerobic culture in vitro. 5. The results obtained support the view that the altered lactate dehydrogenase isoenzyme pattern of urine in renal ischaemia may be explained by anaerobic changes in the lactate dehydrogenase isoenzyme pattern of cortical tubule cells.