Polylysine-coated culture surfaces are strongly adhesive for neural cells, restrict locomotion on nonneuronal elements, but do not inhibit neurite elongation. In the present study, culture dishes were pre-treated with poly-d-lysine (PDL) at various concentrations, seeded with dissociates from 8-day chick embryo dorsal root ganglia, and incubated under conditions that normally support both neuronal survival and nonneuronal proliferation. Pretreatment with low (0.1 mg/ml) PDL concentrations had no effect on neuronal survival and neuritic growth, but entirely prevented an increase in ganglionic nonneurons, yielding a numerically stable culture greatly enriched in neurons. Higher PDL concentrations caused increasing losses in both cell classes. The 50 levels of cell loss were achieved at about the same PDL dose, but earlier for neurons than nonneurons and still with no impairment of neuritic growth from the surviving neurons. A procedure was developed to compare acid-soluble and acid-precipitable accumulation of radioactivity under 1-hr pulses of 3Huridine, which was applicable even to poorly attached cells. The cytotoxic effects of higher PDL pretreatments was revealed as early as 6 hr after seeding by 2- to 4-fold lower radioaccumulation. The data are discussed in terms of possible regulations of cell permeability and metabolism by adhesive interactions between cells and their substratum, or other cells.
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