Role of glycolysis in adenylate depletion and repletion during work and recovery in teleost white muscle.

Measurements of metabolite concentrations before and immediately after swimming of trout to exhaustion indicate that all three potential endogenous fuels of anaerobic metabolism [glycogen, phosphocreatine (PCr) and adenosine triphosphate (ATP)] are utilized during anaerobic white muscle work. Lactate, H+, creatine Pi, NH4+ and inosine monophosphate (IMP) are formed in the process. Glycolysis is considered to be functionally (if loosely) coupled to adenylate depletion by setting up conditions favouring AMP-deaminase-catalysed formation of IMP and NH3. During recovery under these experimental conditions, glycolysis appears to outcompete oxidative metabolism as an ADP acceptor; therefore, in this kind of white muscle, glycolysis is also linked to IMP reconversion to AMP and thus to adenylate replenishment. The net process generates H+, which is why ATP replenishment must be completed before PCr concentrations can be returned to pre-exercise values.