FIG. 6.

Endogenous microvascular NO production is attenuated after particle inhalation in a dose-dependent manner. Endothelial NO production was stimulated by a bolus dose of A23187 and measured real time with an electrochemical sensor. NOS inhibition was accomplished by coincubation with L-NMMA during measurements. Top panel, fine TiO₂: 8 μg, n = 9; 20 μg, n = 9; 36 μg, n = 7; 67 μg, n = 8; 90 μg, n = 9; Sham-Control, n = 34. Bottom panel, nano-TiO₂: 4 μg, n = 6; 6 μg, n = 8; 10 μg, n = 6; 19 μg, n = 6; 38 μg, n = 6; Sham-Control, n = 34. a, p < 0.05 versus Sham-Control group. b, p < 0.05 versus 36 μg fine TiO₂ group. c, p < 0.05 versus 6 μg nano-TiO₂ group. d, p < 0.05 versus 10 μg nano-TiO₂ group. *p < 0.05 versus normal PBS in the same group. Values are means ± SE.