Figure 1.

Tetramethylpyrazine (TMP) protects against hydrogen peroxide- (H₂O₂-) induced endothelial dysfunction. Phenylephrine (Phe, 0.3 μM) was utilized to provoke contraction in isolated rat aortic rings, and acetylcholine (ACh, 3 nM–10 μM) was utilized to induce EDR in the Phe-contracted rings. (a) Representative traces of ACh-induced EDR in H₂O₂ (200 μM)-exposed rings, with and without TMP (10 nM) pretreatment, and control rings. (b), (c) Effects of various drug treatments on H₂O₂-provoked disruption of ACh-induced EDR. The graphs share the same data for the control and H₂O₂-treated groups. Data represent the mean ± the standard error of the mean (SEM) of 4–6 independent experiments (*P < 0.05 versus control; ^# P < 0.05 versus H₂O₂).