Effects of hypoxia and BPS on BrdU incorporation in cultured HPASMC. Cultured HPASMC were exposed to various concentrations of oxygen and BPS in the presence of BrdU for 24 hours. (a) Severe hypoxia (0.1% oxygen) suppressed, whereas moderate hypoxia (2% oxygen) significantly enhanced BrdU incorporation. *P < 0.05 versus 21% oxygen. (b) BrdU incorporation was dose-dependently suppressed by BPS under both normoxic and hypoxic conditions. Data are expressed as means ± SE (n = 6). Open bars, 21% oxygen; solid bars, 2% oxygen. *P < 0.05 versus 21% oxygen control; †P < 0.05 versus without BPS.