Glucose transcapillary transport in the human myocardium: estimation by distributed modeling and a new Monte Carlo method

Glucose transport from the capillary to the interstitium is a crucial kinetic event of glucose metabolism, but it cannot be measured directly in vivo. Here, for the first time, the authors measure transcapillary exchange in the human myocardium from a dual tracer experiment and distributed modeling. The authors applied a multi-pathway distributed model of transcapillary transport to tracer data obtained in the heart of healthy individuals. However, since some parameters are fixed in the standard approach to parameter estimation, the precision of the estimated parameters is likely to be overestimated. To derive a more reliable measure of the precision of parameter estimates and also to check their accuracy, the authors coupled with the distributed model a new Monte Carlo strategy, which takes into account the error associated both with measurement noise and the fixed parameters. Results allow that the distributed model can be successfully employed with multiple tracer data in the human myocardium. Use of the Monte Carlo method demonstrates that the estimated parameters show no bias and that their associated deviation from the mean increases but remains acceptable. Some directions for future research are given.