ABSTRACT
The interaction of calcium and insulin was investigated in mouse mammary gland organ culture by analysis of the time-course of the DNA-synthetic response following delayed addition of insulin or calcium to the culture media. The DNA-synthetic responses were also studied using mammary explants from virgin, pregnant and lactating mice. These experiments have shown that qualitative differences exist in the responsiveness of mammary epithelium to insulin and calcium. Thus, although it is evident that in mammary epithelium calcium modifies the DNA-synthetic response to insulin, the present data do not support the concept that Ca2+ is the intracellular mediator of insulin action.
Subject(s)
Calcium/pharmacology , DNA/biosynthesis , Insulin/pharmacology , Mammary Glands, Animal/metabolism , Animals , Culture Media , Female , Lactation , Mammary Glands, Animal/drug effects , Mice , Organ Culture Techniques , PregnancyABSTRACT
The experiment was conducted on sheep receiving NH4Cl infusions into v. mesentericta anterior. During first 3 h animals received ammonia in a dose of 13 mumol X min-1 X kg body wt.-1 and then next 3 h in a dose of 30 mumol X min-1 X kg body wt.-1. When ammonia was administered in smaller doses its concentration increased to 0.65 and 0.22 mmol/l in portal and peripheral blood, respectively. Simultaneous slight increase of ATP and marked of 2,3-diphosphoglycerate (2,3-DPG) was observed. These effects of moderate ammonia loading are probably caused by the rise of glucose utilization in erythrocytes. Ammonia given in a higher dose induced further rise of its concentration to 1.1 and 0.51 mmol/l in portal and peripheral blood, respectively. Such NH4Cl infusion caused a further rise of 2,3-DPG concentration connected with the drop of ATP level in ovine red blood cells. It seems that a decrease of ATP level was mainly the result of local high 2,3-DPG level which inhibits glycolytic enzymes.
Subject(s)
Adenosine Triphosphate/blood , Ammonia/blood , Diphosphoglyceric Acids/blood , Erythrocytes/metabolism , 2,3-Diphosphoglycerate , Ammonia/pharmacology , Ammonium Chloride/pharmacology , Animals , Osmolar Concentration , Portal Vein , SheepSubject(s)
Blood Coagulation Factors/physiology , Blood Coagulation , Vitamin K/physiology , 1-Carboxyglutamic Acid/metabolism , Calcium-Binding Proteins/physiology , Chemical Phenomena , Chemistry , Glutamates/metabolism , Glutamic Acid , Glycoproteins/physiology , Humans , Microsomes, Liver/metabolism , Models, Biological , Osteocalcin , Protein Binding , Protein C , Protein SABSTRACT
The role of extracellular Ca2+ in the control of DNA synthesis in mouse mammary tissue was studied using mammary gland explants maintained under chemically defined conditions in vitro. Chelation of calcium with ethyleneglycol-bis-(beta-aminoethyl ether) or omission of Ca2+ from the incubation media substantially reduced both basal and insulin-stimulated incorporation of [3H]thymidine into DNA. Addition of calcium to the Ca2+-deficient media restored DNA synthesis; other divalent cations could not be substituted for calcium. Insulin reduced by 5-fold the calcium concentration required to achieve half-maximal stimulation of DNA synthesis in explants, thus indicating that the Ca2+-related process may be involved in the mechanism by which insulin exerts its effect on cell multiplication. Evidence is presented that in mammary gland explants, calcium does not stimulate DNA synthesis by action on the thymidine pool size. Neither calcium nor insulin showed any effect on the activity of thymidine kinase in the mammary gland explants. On the other hand, calcium ions were shown to be necessary to maintain the activity of DNA polymerase-alpha, the enzyme involved in nuclear DNA replication.
Subject(s)
Calcium/pharmacology , DNA/biosynthesis , Insulin/pharmacology , Mammary Glands, Animal/metabolism , Animals , Cations, Divalent/pharmacology , DNA Polymerase I/metabolism , DNA Polymerase II/metabolism , Egtazic Acid/pharmacology , Female , Hydroxyurea/pharmacology , Kinetics , Mammary Glands, Animal/drug effects , Mammary Glands, Animal/enzymology , Mice , Organ Culture Techniques , Thymidine Kinase/metabolismABSTRACT
The experiment was carried out on 85 female breed Wistar rats divided into five groups. All groups of animals except 1 got NH4Cl in the feed in increasing amounts: 2-nd group 1%, 3-rd 2%, 4-th 4% and 5-th group 8%. After two weeks the animals were killed and then the slides of muscles and liver were taken. The levels of ATP, ADP and sum of ATP and ADP in the tissues were marked. In both tissues it was shown that there was an increase of ATP level in the case of higher level of NH4Cl up to 2% and a decrease in cases of lower concentration. Probably the decrease was caused by augmented hydrolysis of ATP to ADP, which is confirmed by the increase of ADP level. We could suppose, that small amounts of NH4Cl (1--2%) accelerate the synthesis of ATP in muscles and liver. The disposal of ADP levels by augmented concentration NH4Cl in fodder is different in both tissues. In the case of muscles there was a decrease of their level to 3-rd group (2% NH4Cl) and an increase to 5-th group. We could presume that further rise of level depends on the penetration of ADP from mitochondria to cytoplasma. The disposal of ADP level in liver is similar to the disposal of ATP. We can see a rise to 3-rd group and a fall to 4-th group. This decrease probably is connected with the production of phosphocreatine needed as a source of energy for the work of muscles.
Subject(s)
Adenosine Diphosphate/metabolism , Adenosine Triphosphate/metabolism , Ammonium Chloride/analysis , Animal Feed/analysis , Liver/metabolism , Muscles/metabolism , Ammonium Chloride/metabolism , Animals , Female , RatsABSTRACT
The experiment was carried out on 40 rabbits divided in four groups. Each animal of the experimental groups received a 850 R dose. X-rays were applied for irradiation. The animals were sacrificed on the 7th, 12th and 17th day after irradiation. Levels of ATP/ADP and phosphocreatine were determined in the skeletal muscles, myocardium, liver, kidneys, blood and the mucosa of duodenum. On the 7th day, in all tissues a decrease of the phosphocreatine level was observed. The lowest level differed little from zero. Afterwards a slow increase of phosphocreatine concentration took place, reaching the normal level in the kidneys on the 17th day after irradiation. The concentration of ATP/ADP was the lowest on the 7th day of the experiment. A fast increase of that fraction was observed in the liver, where the level of ATP/ ADP on the 12th day was higher than in the control group. From the 12th day, a drop in the ATP/ADP level was observed, reaching the normal level on the 17th day. In the skeletal and heart muscles, after a drop on the 7th day, a slow increase of the activity was observed on the last day of the experiment, but the activity did not reach the normal level.
Subject(s)
Adenosine Diphosphate/radiation effects , Adenosine Triphosphate/radiation effects , Phosphorus Metabolism Disorders , Phosphorus/radiation effects , Radiation Injuries, Experimental/metabolism , Adenosine Diphosphate/metabolism , Adenosine Triphosphate/metabolism , Animals , Apoptosis/radiation effects , Duodenum/metabolism , Duodenum/radiation effects , Heart/radiation effects , Kidney/metabolism , Kidney/radiation effects , Liver/metabolism , Liver/radiation effects , Muscle, Skeletal/metabolism , Muscle, Skeletal/radiation effects , Myocardium/metabolism , Phosphorus/metabolism , Phosphorus Metabolism Disorders/diagnostic imaging , Rabbits , Radiation Injuries, Experimental/pathology , Radionuclide Imaging , Radiotherapy DosageABSTRACT
Twenty four rabbits were used in the experiment. The animals were divided into four groups, 6 animals in each. The rabbits were irradiated with a total dose of 910 R. The activity of alkaline phosphatase and the level of inorganic phosphorus were measured on the 5th, 10th and 15th day after irradiation in erythrocytes, plasma, duodenum, muscles and liver. There was found a decrease of phosphatase activity in the plasma, liver and duodenum, and an increase in the muscles and erythrocytes. The level of inorganic phosphorus increased in the duodenum, liver and plasma, and decreased in the muscles and erythrocytes. In the latter two, the increase of the phosphatase activity was accompanied by a decrease of the phosphorus level; on the contrary, the decrease of the enzyme activity in the liver and duodenum was accompanied by an increase of the phosphorus level. During the whole experimental period, the phosphatase activity was higher by about 40% than in the control group.
