ABSTRACT
1. The elucidation of the biochemical controls of growth processes is basic to understanding both normal and malignant growth. The exquisitely sensitive control demonstrated in the regenerating liver provides an excellent model system for growth studies. 2. Intraperitoneal injection of an extract from weanling rat liver into 34% hepatectomized rats stimulates [3H]thymidine incorporation into recipient hepatic DNA 2.5-fold. This stimulation is seen after a 10 hr lag period. 3. Extracts from weanling rat liver contain the highest level of the hepatic regenerative stimulator substance (SS), whereas extracts from adult liver give no significant stimulation. 4. If adult rats are partially hepatectomized, SS is demonstrated in their livers 12-15 hr after hepatectomy. 5. Partial characterization of SS shows that it is a soluble material not sedimented by centrifugation for 2 hr at 145,000 g. The stimulator activity is stable to heating at 65 degrees C and 100 degrees C for 15 min but is lost when treated with 10% perchloric acid.
Subject(s)
Liver Regeneration , Liver/physiology , Age Factors , Animals , Biological Assay , DNA/biosynthesis , DNA/metabolism , Hepatectomy , Male , Rats , Stimulation, Chemical , Thymidine/metabolism , WeaningABSTRACT
Further modifications of the enzymatic technique for the preparation of isolated, intact, parenchymal cells from rat liver as previously described by this laboratory are presented together with a detailed account of several critical factors involved during the procedure. In addition, the fine structure of the cells as revealed by electron microscopy and the characteristics of their respiratory activity in different media and with several added substrates are described. It is shown that cells obtained by adding calcium during the preparative procedure retain approximately 34% more potassium than cells prepared solely in a calcium-free medium. The former cells also demonstrate a higher respiratory activity, which is not due to uncoupling of respiration. Electron microscopy reveals that the cells have an intact plasma membrane and well-preserved intracellular organelles. Glycogen particles are observed in all cells and are particularly abundant when either 20 mM pyruvate is added during the preparation or Eagle's Minimum Essential Medium is employed.
Subject(s)
Cytological Techniques , Liver/cytology , Potassium/analysis , Animals , Calcium/pharmacology , Carbon Dioxide/biosynthesis , Cell Count , Cell Membrane , Cell Separation , Cell Survival , Cells, Cultured , Citric Acid Cycle , Culture Media , Endoplasmic Reticulum , Golgi Apparatus , Hydrogen-Ion Concentration , Liver/analysis , Liver Glycogen/isolation & purification , Male , Microscopy, Electron , Mitochondria, Liver , Oxygen Consumption/drug effects , Pyruvates , Rats , Succinates/pharmacologySubject(s)
Nurses , Delivery of Health Care , Health Education , Humans , Interprofessional Relations , PhysiciansABSTRACT
Suspensions of isolated parenchymal cells were prepared from rat liver by incubation with collagenase and hyaluronidase followed by mechanical treatment. Utilization of 0.15% collagenase together with 0.15% hyaluronidase yielded adequate numbers of cells for experimental purposes. As shown by light and electron microscopy, approximately 75% of the isolated cells retain their structural integrity. The cell suspensions are capable of maintaining endogenous respiration in the presence of 1% albumin for periods of time up to 8 hr. These cell preparations consist almost entirely of parenchymal cells and offer a unique tissue preparation for the study of hepatic metabolism.
