Figure 6

Protective effects of TQ-6 on OH· formation by electron spin resonance (ESR) study, closure time according to the analysis on the PFA-100 system and thrombotic platelet plug formation in the mesenteric venules of mice as well as the bleeding time in mouse tail vein. (A) Washed platelets were preincubated with Tyrode’s solution (a, resting control) or treated with (b) 0.5% DMSO or TQ-6 at (c) 0.3 µM or (d) 0.5 µM, followed by the addition of collagen (1 µg/ml) to trigger OH· formation. Profiles are representative of four independent experiments and an asterisk (*) indicates the formation of OH·. (B) Shear-induced platelet plug formation in whole blood was determined by recording the closure time of CEPI-coated membranes, as described in the “Materials and methods.” (C) For another study, mice were administered an intravenous bolus of the solvent control (0.5% DMSO) or TQ-6 (0.4 mg/kg), and the mesenteric venules were irradiated to induce microthrombus formation (occlusion time). (D) Microscopic images (400 × magnification) of 0.5% DMSO-treated controls (a, b) and the TQ-6 (0.4 mg/kg)-treated groups (c, d) were recorded at 5 (a, c) and 150 s (b, d) after irradiation. Photographs are representative of six similar experiments. Arrow indicates platelet plug formation. (E) The bleeding time was measured through transection of the tail in mice after 30 min of administering either 0.4 mg/kg TQ-6 or 150 mg/kg aspirin intraperitoneally. Data are presented as means ± standard errors of the means (B,C, n = 6; E, n = 8). *p < 0.05, **p < 0.01, and ***p < 0.001, compared with the solvent control (0.5% DMSO or PBS)-treated group.