Figure 4. COS-7 cells transfected with hPGHS-2 consume NO following H₂O₂ addition faster than controls.

(A) NO consumption of COS-7 cells was determined as described in the Experimental section, following addition of 500 μM H₂O₂ to 1 ml of PBS containing 5×10⁶ cells and 1 mM CaCl₂ (n≥3; means±S.D.). Bars represent rates of NO decay for cells in the presence or absence of H₂O₂, as appropriate. ***P<0.05 compared with control (unpaired t test). (B) Representative traces from (A): (i) NO decay in PBS containing 5×10⁶ PGHS-2-transfected COS-7 cells and 1 mM CaCl₂; (ii) 500 μM H₂O₂ was added to PGHS-2-transfected COS-7 cells in (i); (iii) NO decay in PBS containing 5×10⁶ control COS-7 cells and 1 mM CaCl₂; (iv) 500 μM H₂O₂ was added to control COS-7 cells in (iii).