Inhibition of cell differentiation by quinolones in micromass cultures of rat embryonic limb bud and midbrain cells

In LB cultures all three drugs were cytotoxic (P/D ratios were ⩽1). In CNS cultures P/D ratios were ⩾1 (up to 2.7 for Nor, up to 4.4 for Enr and up to 16 for Cip) what can suggest specific action on differentiation. Ciprofloxacin was the most toxic and CNS cells were more sensitive than LB. The ranges of IC50-D values (μg/ml) were as follows: Nor (79-14), Enr (127-179), Cip (91-101) in LB cultures; Nor (22-52), Enr (38-91), Cip (3-17) in CNS cultures. With one exception (Cip in CNS culture) all drugs were classified as weak embryotoxic.