RESUMEN
The [3H]hydrocortisone transfer into intact target cells and into non-target cells, e. g. isolated hepatocytes, hormone-sensitive Morris hepatoma 7777 cells, hormone-resistant Zajdela ascite hepatoma cells, was studied. In target cells the glucocorticoid transfer is temperature-dependent, i. e. the curve for hormone binding by the cells at increasing concentrations shows a plateau Phospholipase A2 and neuraminidase decrease the ability of the cells to incorporate the labelled hormone. The experimental data differ significantly from those obtained for target cell cytosol and for intact Zajdela hepatoma cells. It was assumed that in target cells the crucial role in hormone transfer into the cells belongs to plasma membranes, while in non-target cells the hormone penetrates inside the cells by passive diffusion.
Asunto(s)
Hidrocortisona/metabolismo , Neoplasias Hepáticas Experimentales/metabolismo , Animales , Transporte Biológico , Membrana Celular/metabolismo , Cinética , Masculino , RatasRESUMEN
The rat hepatocytes during chemical carcinogenesis (3'-MDAB), as well as the cells of chemically-induced primary rat hepatomas preserved their response to partial hepatectomy by stimulation of the 3H-thymidine incorporation into DNA; as in the normal liver this process is inhibited by dexamethason. No impairment in the inducibility of tyrosine aminotranspherase (EC.2.6.1.5) by the hormone was observed, whereas the hormonal induction of tryptophane pyrrolase (EC.1.13.11.11) in primary hepatomas was lost completely. The problem of the adequacy of the model of chemical carcinogenesis of the organ without consideration of the cell populations heterogeneity is discussed.
Asunto(s)
Glucocorticoides/farmacología , Neoplasias Hepáticas Experimentales/inducido químicamente , Hígado/efectos de los fármacos , Animales , ADN de Neoplasias/biosíntesis , Dexametasona/farmacología , Inducción Enzimática/efectos de los fármacos , Hepatectomía , Indolamina-Pirrol 2,3,-Dioxigenasa , Masculino , Metildimetilaminoazobenceno , Ratas , Timidina/metabolismo , Factores de Tiempo , Triptófano Oxigenasa/biosíntesis , Tirosina Transaminasa/biosíntesisRESUMEN
Sepharose 4B column with antibody to tyrosine aminotransferase (E.C. 2.6.1.5) (TAT) covalently bound can selectively remove a specific fraction of TAT polysomes from rat liver homogenates. From the polysomes which was adsorbed by immunosorbent one may obtain mRNA containing a segment of poly-adenilate-rich residues, having sedimentation constant of 11--16S. This mRNA may program synthesis of the specific protein in a cell free system. Near 70% of the protein was synthesized in such a system, may react with the antibody to TAT.