Hello everybody, I wonder if it is possible to increase ATP levels in mice just giving them water with Glucose in order to push glycolysis. I am working with a liver KO model where OXPHOS seems to be compromised and I would like to test if the morphological changes I can see at cellular level are due to an energy defect. As changing the diet of the animals would take longer, I wonder if it is possible to supply those animals water with some concentration of Glucose in order to push Glycolysis and somehow restore ATP levels. Thanks
You can also try with body-building supplements added to the rodents diet. These are rich in fast ATP supply elements, i.e. creatin, citrullin malate or pyruvate.
David, ATP is an intracellularly regulated parameter. Unless you have a math model of liver cell metabolism, it would be hard, by modifying just one input, to predict the outcome. I think you heve left trial and error. And keep your records well organized because I do not thnk that question has been answered experimentally.
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A lot of efforts are done by cells to keep the ATP level up and running at constant levels as Juan hints, so in order to have an estimate of the actual energy status you would actually need to have the profile of both ATP, ADP and AMP determined, as well as other high energy endogenous metobolites...
I do not know about a liver KO model in rat, but, since nucleotide de novo synthesis is performed mainly in the liver I suggest to give some adenine or hypoxanthine to your rats. Also you could try with inosine that will give to the animals both purine base and sugar for energy repletion. Good luck
Adding glucose to the water is unlikely to increase ATP levels. ATP production is regulated largely by demand (i.e. ADP). The exception would be if substrate is severely limited. Do these mice have normal circulating glucose? Can they perform gluconeogenesis in the liver? If both of these are true, then glucose will not be helpful.
Also, I absolutely agree with Birger in that energy status is not solely determined by the concentration of ATP but rather the ratio of ATP:ADP. This ratio, along with the Pi concentration, defines the free energy available from ATP hydrolysis.
I assumed your experimental model is exercising mice. Are you asking for a prolonged effort capacity? As explained above by several contributors, at rest, ATP intracellular levels are so tightly regulated that it is unlikely to be changed in a way that can be effectively measured. However, changes in ATP, ADP an Pi levels and proportions have been measured by RMN in human skeletal muscle during muscle contraction.
I agree with the comment of most of the posters but there are methods to temporarily increase intracellular ATP levels rapidly in hepatocytes. The rate limiting step for glycolysis, assuming all enzymes are present and stimulated by insulin, would be glucokinase. The Km of glucokinase for glucose is in the order of 10 mM. This is a common dilemma for cultured cells (exposing them to non physiological glucose levels) but that is a seperate issue. Because glucose availability is limited intracellularly by the enzyme glucokinase, it is virtually impossibly to significantly change ATP energy generation via glycolysis and respiration. To raise the glucose levels to 10 x the Km would mean the cells are exposed to ~100 mM glucose which is a major change in osmolality. As some posters have noted look to another energy substrate. If you are dealing with cultured cells, you can expose them to fructose in the order of 5 mM. The Km for fructose by fructokinase is in the order of 0.5 mM so this would represent a 10 x the Km number and not affect osmolarity much. All you can hope for is a bump in ATP levels for a period of time followed by a crash. The consumption of ATP by fructo/gluco-kinase will likely drop ATP later. ATP generation by the mitochondria will likely not change but ATP consumption by kinases will continue unabated till Km met. This strategy has been employed in the realm of tissue preservation.
It is important to note that the mitochondrial energy generation will likely NOT be affected by the increase in fructose or glucose. The bump in ATP will be purely from glycolysis. To get the mitochondria to increase ATP production would not be advised because you will have a very hard time controlling your experiments. ROS generation will increase. If you think mitochondria are different in KOs, then isolate the mitos and examine their ability to generate ATP in controlled conditions with various complex inhibitors.
Hi Dave,
Galactose forces the cells to go through oxidative phosphorylation which we all know would give more ATP. Any other method that would increase the expressions of Electron Transport Chain Enzymes and FoF1ATPase might work. I think the use of galactose might save the day. You can give a high concentration of galactose.
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