Figure 5. Mitochondrial H₂O₂ mediates sTNF-α–induced TNFR1 shedding.

DCF (2.5 μM). (A) roGFP fluorescence in mouse lung endothelium. Dashed lines indicate microvascular walls; arrow denotes direction of flow. Scale bar: 25 μm. (B and C) Single experiment (B) and group data (C) showing endothelial roGFP fluorescence responses after infusion of sTNF-α (1 ng/ml, 10 minutes) in the presence of MitoQ (100 nM) or vehicle (Veh; ethanol). H₂O₂ (10 μM) was administered by microvascular micropuncture. (D) Group data for DCF-loaded microvessels infused with sTNF-α in the presence or absence of MitoQ or in lungs from mice transfected with cCAT or mCAT. Responses in vector-transfected animals were not significantly different from control (n = 3 for each empty vector; not shown). (E) Effect of ROS inhibition on sTNF-α–induced shedding of TNFR1 determined in single microvessels. *P < 0.05 versus baseline or control; ^#P < 0.05 versus sTNF-α.