ABSTRACT
The in vivo study of transport of radiotracers is hindered by many variables, such as hormonal, immunological, nervous, vascular factors, and by the presence of different cell types in the tissue studied. The transport across the cell membrane depends on the magnitude of the molecules considered. The use of an in vitro system has the advantage of analyzing single parameters involved in the radiotracers transport mechanism. The fast rate of glucose transport found in transformed cells is probably correlated to the high glycolytic rate of transformed cells. Isolated biological membranes have an important role in the study of the mechanism of transport. The use of in vitro system allows the identification of the function the plasma membrane performs in regulating the accumulation of radiotracers. Many studies were already made with cell cultures using different systems. A distinction should be made between primary cultures and cell lines.
