O. Suschny

Radiochemical investigation of the utilisation of glucose by tissue cultures

Abstract The aerobic production of carbon dioxide and of lactic acid from radioactive glucose by chicken fibroblasts and by HeLa tumour in vitro has been investigated. The ratio of glucose carbon converted into lactic acid and into carbon dioxide, respectively, has been called q-value. Generally, the q-values of fibroblasts are low in conditions favourable for survival. After explantation or transplantation, the q-values are high, and go down only as the tissue adapts itself to new conditions. However, scarcity of the metabolic fuel glucose also tends to decrease the value of q, and very low q-values are observed when the fibroblasts are kept starving in isotonic salt solution. With HeLa, no conditions have been found where respiration predominates over glycolysis. Though for both HeLa and fibroblasts conditions can be adjusted so that far more glucose is glycolysed than oxidised, respiration seems to play a role in fibroblasts, which is qualitatively different from that in HeLa. In view of the strong dependence of q on experimental conditions, these must be standardised strictly, if different kinds of tissue are to be compared.

Effects of trypsin treatment on tissue in culture

Abstract The influence of controlled damage on the growth and the energy metabolism of tissue in culture was studied. In the preparation of monolayers of chick mesenchyma tissue the time of treatment with trypsin was varied. Thereafter, the cells in the roller tubes were counted at time intervals. At first, fewer cells were found in the tubes where trypsin treatment had been more prolonged, but after 5 days all cell counts were similar. The production of CO 2 and lactic acid from radioactive glucose were also measured in the time interval from the third to the fifth day after treatment with trypsin. Depressed respiration and increased fermentation were found. It is suggested that the damage to respiration is, in part, compensated by an increase in fermentation.

Effects of hydrogen ion concentration on tissue in culture.

Abstract Monolayer cultures of chick mesenchyma tissue were grown in media of various pH values (initially 6.0–8.5) but otherwise identical. The tissue displays a remarkable power to adjust the pH value of the medium in the direction of pH 7.5. The fastest increase in cell counts was obtained when the initial pH value was about 7.5. In some experiments, radioglucose was contained in the medium. The amount of radioactive CO 2 and lactic acid produced during incubation increased with increasing pH value. In tubes containing large numbers of cells, fermentation was more enhanced by increasing alkalinity than was respiration.

Production of carbon dioxide and lactic acid from radioactive glucose by tissue in culture

Abstract Chick embryo mesenchyma tissue in culture (mostly monolayers with known numbers of cells) was incubated in growth-promoting nutrient media with radioactive glucose, the carbon dioxide and the lactic acid isolated, and their radioactivities determined with the gas Geiger counter. Both “synthetic” and “natural” media were used. Some experiments were also done with tissue kept in salt solution. As the number of cells per unit quantity of glucose increases, glycolysis per cell decreases and respiration per cell increases, as far as glucose serves as the substrate. Thus the Crabtree effect in tissue culture is at least partly due to a switch from the utilization of glucose by respiration to its utilization by glycolysis (“one-substrate” theory). The effects of controlled damage by trypsin resemble those of an increase in the supply of glucose. In all experiments with growth-promoting media more glucose is glycolyzed than respired, but more free energy is usually derived from respiration than from glycolysis. The total amount of free energy derived from glucose, per cell, does not change significantly as the supply of glucose per cell is varied. No major differences in the utilization of glucose are observed in the given conditions between monolayers and solid tissue pieces.

Fortschritte bei der Herstellung radioaktiver Zucker

Nach einer verbesserten Methodik wurden gegenuber fruheren Ergebnissen1 in groserer Ausbeute Zucker erhalten, die erheblich reiner sind und deren spezifische Aktivitat 5 bis 10mal groser ist.

Untersuchung der Atmung einzelner Gewebekulturen mit Radiokohlenstoff

In Embryonalextrakt gehaltenen Kulturen von Huhnchenfibroblasten wurde radioaktive Glukose zugefuhrt und die Aktivitat des erzeugten Kohlendioxyds bestimmt. Aus dieser Aktivitat wurde auf die veratmete Glukosemenge geschlossen. Deckglaskulturen veratmeten bei Zufuhr von 6 γ oder mehr Glukose 1 γ. Nach einigen Stunden wurde ein Maximum der Atmung erreicht, nach wenigen Tagen kam die Atmung praktisch zum Stillstand. Auch Embryonalextrakt allein (ohne Kultur) entwickelt eine geringe Menge Radiokohlendioxyd.Roller-Kulturen veratmen viel mehr (unter Umstanden hundertemal mehr) Glukose als Deckglaskulturen; auch in diesem Falle ist die Kohlendioxydentwicklung der Kultur viel groser als die des Nahrmediums. Deckglas- undRoller-Kulturen veratmen Glukose auch in isotoner Salzlosung ohne Zusatz von Embryonalextrakt.