[Changes in the electrokinetic characteristics of hepatic cells in young rats after treatment with isoprenaline].

The changes of the charge group density on the cell membrane and the role of the sialic acid residues were studied in the liver cells of rats treated with high doses of isoprenaline in various organs with effects at genetic, structural and metabolic level. The postnatal growth of the rat liver was followed, when a process of polyploidization occurs: IPR treatment in this period is known to accelerate the phenomenon. IPR was injected twice a day intraperitoneally at the dose of 2 mg/100 g of body weight in one or two week courses. The charge group density was evaluated from the electrophoretic mobility pattern of isolated hepatocytes using the Zeiss cell electrophoresis apparatus. The presence and the importance of sialosubstances in the cell membrane was evaluated by comparing the data from normal cells with neuraminidase treated cells; in this situation, the release of sialic acid by neuraminidase produced significant reductions of the cellular electrophoretic mobility. A general increase of the surface charge density, mostly due to the sialic acid fraction, was demonstrated in association with the IPR treatment; this effect was more evident at later times after the end of the stimulation and in animals treated with two courses of IPR. This study evidenced the role of the membrane sialomucinic component during the whole sequence of events induced by IPR treatment at cytological level and leading, among other things, to a mitotic stimulation. In addition, the persistence of the high charge group density should be taken into account even in connection with cell growth, differentiation and hypertrophy.