Inhibition of gap‐junctional intercellular communication and enhanced binding of fibronectin‐coated latex beads by stimulation of DNA synthesis in quiescent 3T3‐L1 cells

To clarify the modulation of intercellular communication via gap junctions, associated with the growth induction of quiescent 3T3-L1 cells, we investigated -the gap-junctional intercellular communication in growth-stimulated cells that were able to bind fibronectin-coated beads. When quiescent 3T3-L1 cells were incubated with fibronectin-coated beads for the first 2 h after the addition of calf serum, 24.0% of the cells bound and phagocytosed beads. Among the cells with bound beads, the percentage of the cells labeled concurrently with bromodeox-yuridine was 63.7% when examined 13 h after the addition of calf serum. Transient reduction of dye-coupling, measured with Lucifer Yellow CH, was observed only in the cells with bound beads 2 h after addition of calf serum, but it was not observed in the cells without bound beads. When the quiescent cells were incubated with fibronectin-coated beads for 2 h from 4–6 h after the addition of calf serum, the percentage of cells with bound beads increased to 53.1 %, but the decrease in dye-coupling among the cells with bound beads was slight. These results suggest that the induction of cell growth causes a transient reduction in gap-junctional intercellular communication in 3T3-L1 cells with bound fibronec-tin-coated beads.