On the Mechanisms of ATP-Induced and Succinate-Induced Redistribution of Cations in Isolated Rat Liver Cells
Article first published online: 3 MAR 2005
European Journal of Biochemistry
Volume 131, Issue 2, pages 247–254, March 1983
How to Cite
KRELL, H., ERMISCH, N., KASPEREK, S. and PFAFF, E. (1983), On the Mechanisms of ATP-Induced and Succinate-Induced Redistribution of Cations in Isolated Rat Liver Cells. European Journal of Biochemistry, 131: 247–254. doi: 10.1111/j.1432-1033.1983.tb07256.x
- Issue published online: 3 MAR 2005
- Article first published online: 3 MAR 2005
- (Received September 2/December 7, 1982) – EJB 5959
- 1The ability of external ATP to induce calcium uptake in isolated rat liver cells was further characterized. Stimulation of calcium uptake was specific for ATP, other nucleotides or ATP metabolities had no comparable effect. ATP was dephosphorylated while stimulating calcium uptake, but there was no stoichiometry between ATP hydrolysis and calcium uptake nor did dephosphorylation depend on calcium concentration. ATP acted from outside and was dephosphorylated by an ecto-ATPase of the cells.
- 2In addition to its direct action, ATP enhanced succinate-dependent calcium uptake in a cooperative fashion. This is best explained by differnt sites of action. ATP increases cell membrane permeability while succinate stimulates uptake into mitochondria.
- 3ATP was able to lower Na+ and K+ gradients and the pH gradient between cells and incubation medium. Increasing calcium concentration counteracted this effect though calcium uptake was then stimulated.
- 4Succinate alone did not affect monovalent cation gradients but raised the pH gradient. It partially counteracted the ATP effects on these gradients.
- 5Since catecholamine-like actions of ATP may be mediated by an increase in cytoplasmic calcium concentration, the action of extracellular ATP can be taken as a model to study the role of calcium as a transmitter of hormone actions. From interdependence between ATP-stimulated and succinate-stimulated calcium uptake, conclusions can be drawn on the resulting cytoplasmic calcium concentration and its effect on plasma membrane permeability.