Computer Modeling of Nonsteady State Sodium Kinetics in Liver

The exchange of materials in biologic tissues can be quantitatively described by transport rate constants (k´s). One way to determine these k´s is from studies of tissue fragments with the aid of an isotope as tracer and digital computer simulation. Usual methods of solution require that the material of interest, tracee, remain at steady state during the in vitro outflow recording period. When Na kinetics is studied in liver fragments, it is found that this tissue keeps absorbing Na tracee from the in vitro medium, thus departing from in vivo and yielding a nonsteady state.