|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1992 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1991 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1990 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Many investigators have studied the mechanism of liver regeneration after partial hepatectomy. Recently, hepatocyte growth factor, originally found in the serum of partially hepatectomized rat and platelets, is a most potent mitogen for hepatocytes in vivo. I therefore performed the present investigation of rat hepatocyte proliferation in vivo following partial hepatectomy carried out under thrombocytopenic condition and/or a significant reduction of platelet activity. Animals were divided into 4 groups, A. hepatectomy only, B. hepatectomy + thrombocytopenia, C. hepatectomy + the reduction of platelat, D. B + C.
[Result] The regeneration rate in the D group had been significantly lower than that of the other groups from 4th postoperative day. There were no significant difference in liver regeneration between the other three groups. DNA synthesis in four groups increased significantly from the control values (the operative day) on the first and the second postoperative day, and it returned to the control level from four days after the operation. But compared to the other group, DNA synthesis in D group decreased significantly. DNA content in the four groups increased from control values after the operation, but decreased significantly in D group after the second day between the other groups. Regenerating rat hepatocytes in the four groups, isolated and cultured under identical condition, showed two different population of cells, diploid and tetraploid cells. Analysis of cell cycle by flow cytometry showed that compared to the other groups, D group's hepatocytes in G1 state on the fourth day increased about 15%, decreasing the proportion of cells in the S and G2 + M state.