Cell cycle and 5'-Nucleotide phosphodiesterase activities in rat liver.

The postnatal developments of liver and serum 5'-nucleotide phosphodiesterase (5'-NPD) in Fischer 344 rats were studied. The liver enzyme activities were found to correlate well with the growth of the liver as measured by the wet weight and percentages of liver cells in the G2/M phases of the cell cycle as determined by flow cytofluorometry. Therefore, this enzyme may be intimately related to the growth of the liver. Although the specific activities of the serum enzyme are three orders of magnitude less than that of the liver enzyme, very good correlation was obtained between the total serum and liver enzyme activities. This finding, therefore, suggest that the main origin of the serum enzyme is from liver. Multiple isozymes were detected in both liver and serum 5'-nucleotide phosphodiesterase after polyacrylamide gel electrophoresis.