Graham Kemp1, Nicole van den Broek2, Klaas Nicolay2, Jeanine Prompers2
1Magnetic Resonance and Image Analysis Research Centre , University of Liverpool, Liverpool, Merseyside, United Kingdom; 2Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands
In 31P MRS studies of recovery from exercise the pH-sensitivities of acid efflux and PCr recovery time constant are correlated, suggesting that intersubject differences in the latter are related to differences in cellular pH control. A simple model of ADP-dependent oxidative ATP synthesis and pH-dependent acid efflux reproduces the pH-dependence of PCr recovery. Here we show that it directly predicts the effect of efflux on this, and indeed also individual values of the PCr and ADP time constants, but that this depends also on the relationship between end-exercise pH and [PCr], which is not under direct experimental control.