Adrenalin has differential effects on epidermal cell cycle progression in mice.

The cell kinetic response after intraperitoneal injection of the 10 micrograms adrenalin was investigated in hairless mouse epidermis. Changes in the proportion of cells in S and G2 phase were studied by means of flow cytometry of isolated basal cells. Changes in the proportion of cells in prophase and metaphase, changes in the mitotic rate (Colcemid method) and in cell cycle progression of 3H-TdR labeled cells were studied in histologic sections. The results showed that adrenalin has a differential effect on cell proliferation in mouse epidermis. The cell progression rate from S phase through G2 phase to metaphase is increased in one cohort of cells shortly after adrenalin injection. Simultaneously another cohort of cells is reversibly delayed or blocked in prophase. In agreement with most previous studies a significantly reduced cell division rate was seen 2-3 hr after adrenalin injection. At this time the proportions of cells in prophase and G2 phase were normalized, whereas a significant increase in the proportion of cells in S phase had cycle progression out of S phase might be responsible for the reduced mitotic rate seen after adrenalin administration.