AMP deamination delays muscle acidification during heavy exercise and hypoxia.

In silico studies carried out by using a computer model of oxidative phosphorylation and anaerobic glycolysis in skeletal muscle demonstrated that deamination of AMP to IMP during heavy short term exercise and/or hypoxia lessens the acidification of myocytes. The concerted action of adenylate kinase and AMP deaminase, leading to a decrease in the total adenine nucleotide pool, constitutes an additional process consuming ADP and producing ATP. It diminishes the amount of ADP that must be converted to ATP by other processes in order to meet the rate of ADP production by ATPases (because the adenylate kinase + AMP deaminase system produces only 1 ATP per 2 ADPs used, ATP consumption is not matched by ATP production, and the reduction of the total adenine nucleotide pool occurs mostly at the cost of [ATP]). As a result, the rate of ADP consumption by other processes may be lowered. This effect concerns mostly ADP consumption by anaerobic glycolysis that is inhibited by AMP deamination-induced decrease in [ADP] and [AMP], and not oxidative phosphorylation, because during heavy exercise and/or hypoxia [ADP] is significantly greater than the Km value of this process for ADP. The resultant reduction of proton production by anaerobic glycolysis enables us to delay the termination of exercise because of fatigue and/or to diminish cell damage.