Computed average rate of the glutamate-glutamine cycle versus average OGI. Simulations show that the average Vcyc increases as the average OGI decreases, consistently with the underlying relationship between OGI and glucose uptake. The curves represent conditional averages, computed over solutions characterized respectively by Vcyc ≥ 0, and Vcyc > 0. The red dashed line identifies the awake resting state (OGI = 5.5). The crossing points between the line at OGI = 5.5 and each of the two curves identify the values of Vcyc relevant for the basal conditions. Specifically, Vcyc is roughly 0.06 or 0.08 for the groups Vcyc ≥ 0 and Vcyc > 0, respectively. The two curves are significantly different for OGI . This is consistent with the fact that the contribution of solutions with Vcyc = 0 becomes negligible at high activation levels.
Massucci et al. BMC Systems Biology 2013 7:103 doi:10.1186/1752-0509-7-103