title: Two types of growth inhibitor in rat platelets for primary cultured rat hepatocytes.
abstract: Rat platelets contain two types of growth inhibitor of adult rat hepatocytes in primary culture. One, named platelet derived growth inhibitor (PDGI)-alpha, is a heat- and acid-labile protein with a molecular weight of over 200 KD that is not released on thrombin treatment. The other, named PDGI-beta, is a heat- and acid-stable factor with a molecular weight of 24 KD that is released by thrombin. Both PDGI-alpha and -beta were inactivated by treatment with dithiothreitol. They both caused dose-dependent inhibition of DNA synthesis stimulated by insulin plus epidermal growth factor. These inhibitions were closely correlated with marked decrease in the labeling index. Neither PDGI-alpha nor -beta had a cytotoxic effect as judged by phase-contrast microscopic examination of the cells nor inhibition of protein synthesis. The properties of PDGI-beta suggest that it may be identical with transforming growth factor-beta. These results indicate that rat platelets contain not only a growth factor (HGF), but also growth inhibitors that affect adult rat hepatocytes.
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000032:analysis* / Q000187:drug effects; D001798:Blood Proteins / Q000032:analysis* / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D006131:Growth Inhibitors / Q000097:blood* / Q000494:pharmacology; D006358:Hot Temperature; D007328:Insulin / Q000494:pharmacology; D008099:Liver / Q000166:cytology*; D008970:Molecular Weight; D051381:Rats; D013917:Thrombin / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D006131:Growth Inhibitors; D007328:Insulin; D004247:DNA; D013917:Thrombin