Kinetics of absorption of perorally applied carbon-14 arginine in Japanese quail (Coturnix Coturnix Japonica)

A mathematical model of the kinetics of the arginine transfer in a three-compartment system with a 'run-off' has been developed. The changes in arginine concentrations in the compartments were described by differential equations for various relations between 'carrier transport' and diffusion. For verification of this model and evaluation of some parameters, informative experiments with L-arginine (U-14C) and (guanido-14C) were carried out by continuous recording of specific activity in blood at extracorporeal circulation. The specific activity in TCA soluble fractions of various tissues after a peroral application of arginine was determined. The maximum of 14C activity in blood was reached in the time between 150 to 210 minutes after application. Three different kinetics were observed for each curve. By continuous recording of radioactivity in blood after iv application, two phases have been evaluated in the declining part of the curves indicating the possibility of the existence of two compartments in the cell. With arginine labelled in the guanidine group the radioactivity in the TCA soluble fraction was first increased in liver and in GI tract, and only later in kidneys and in muscles. (author)