Undisturbed generation of ATP, produced through NADH dehydrogenase in the respiratory chain, is required for the homeostasis of aerobic metabolism.
The heart requires rapid production of ATP where there is complete turnover of ATP every 10 seconds with 90% of ATP produced by mitochondrial oxidative metabolism requiring substrates of approximately 30% glucose and 65% fatty acids.
The specific kinetic features of glucokinase, the gatekeeper of ATP synthesis process, make the amount of the ATP produced fairly proportional to the glucose concentration outside the beta cell.
Nonetheless, this is not as dramatic as would be expected based on the contribution that mitochondrial oxidative phosphorylation normally makes to ATP generation (i.e., ∼90% of total ATP produced).
In this study, we have demonstrated that the ANLSH is more advantageous for the neuron in terms of ATP produced, both under hypoxic and normoxic conditions, although it does not provide a significant advantage for the astrocyte.
The evolutionary pressure for the protein factory to increasingly surround the ATP producer is clear, as this means that it can obtain all the ATP produced and thus receive all the benefit of the proteins, pyruvate, and ADP it is providing to the ATP producer.
Under these conditions, the amount of ATP produced in the astrocyte with the ANLSH under any condition is very low, this ATP can not sustain normal astrocytic functions for very long, however it is certain that a temporary ANLSH would benefit the neuron enormously even with a single mitochondrion; the output will be much higher for a neuron with multiple mitochondria seen in vivo.
Lastly, some (astrocytic) biochemical processes, such as ATP-consuming membrane pumps, depend on ATP produced by substrate-level phosphorylation in the glycolytic pathway rather than the bulk pool of ATP; this might be explained by the formation of supramolecular complexes of enzymes and transporters such that at least some glycolytic ATP never enters the bulk cytosol (Schousboe et al., 2011).
HKI benefits from preferential access to ATP produced in the mitochondria, while local ADP generation by HKI facilitates the exchange of ADP and ATP through the inner mitochondrial membrane [8], [9].
Butyrate production leads to 0.5 mole of ATP produced whereas acetate production leads to 1 mole of ATP produced for every pyruvate consumed.
The flux map indicates that 51 69% of the ATP produced is used for biomass synthesis and up to 47% is expended in substrate cycling.
