An initial characterization of a mitostatic activity for hepatocytes and renocytes in extracts from adult mouse liver. 
We have previously demonstrated that liver extract, when administered at 16:00 hr, inhibits the mitotic activity of hepatocytes and renocytes at 08:00, 12:00 and 16:00 hr.  during the following 2 days.  The experiments reported here were designed to achieve an initial characterization of this liver mitostatic activity.  For these studies we used 28-days-old male C3HS mice injected with either saline, liver extract (LE), mitochondrial-pellet extract (MPE), or postmitochondrial supernatant (PMS) at a dose of 1.9 mg of protein/g body weight.  Colchicine (2 microg/g) was injected 4 hrs.  before sacrifice and the number of arrested metaphases within the hepatocyte and renocyte population was estimated.  The mice treated with LE were killed at (time of day/hr.  post injection) 16/08:00, 20/12:00 and 24/16:00; while those injected with MPE or PMS were sacrificed at 20/12:00.  We found that both the LE and the PMS inhibited the mitotic activity of hepatocytes and renocytes, while MPE reduced the mitotic activity of the liver cells without affecting that of the renal population.