The effect of a body burden of methylmercury on hepatic regeneration.

The model of hepatic regeneration is chosen to study the effect of methylmercury burden on cell proliferation. The results show that chronic methylmercury burden impedes the rate of thymidine incorporation during the process of DNA synthesis. At 24 hours after partial hepatectomy, thymidine incorporation in the mercury exposed rats is 53% of the controls. Counts of labeled hepatocytes in radioautographic preparations also support this observation. This remarkable difference in DNA synthetic activity at 24 hours also reflects in the DNA content and liver, weights at 72 hours after partial hepatectomy (Liver weights 2.36 +/- 0.21 gm/100 gm B. W. vs. 2.67 +/- 0.31 gm/100 B. W., P < 0,05; DNA contents 160.78 +/- 36.76 microgram/gm vs. 214.80 +/- 37.908 microgram/gm, P < 0.05). After two weeks, no significant difference is noted in liver weight, DNA content and synthetic activity. On the other hand, protein content and biosynthesis in the liver of methylmercury burdened rats shows no significant difference from the controls in all the periods studied. From these data it is concluded that the dividing fraction of hepatocytes is reduced in methylmercury-treated group at an early stage of regeneration when cell proliferation is most active.