Fig. 3. Protection of carbon black N990-induced cytotoxicity by antioxidants, N-acetylcysteine (NAC) and sulforaphane. A-10 cells were pretreated with (A) NAC (10 or 100 μM) or (B) sulforaphane (1 or 10 μM) for 1 hr and exposed to 100 μg/ml of carbon black N990 for an additional 24 hrs. Cytotoxicity was measured by LDH activity released into the medium. Data were obtained from three independent experiments and expressed as mean ± SE of total LDH activity measured from total lysis with 1% Triton X-100. ^#P < 0.05 versus untreated control cells; ^*P<0.05 versus carbon black N990-alone treated cells. Sul, sulforaphane.