COX‐2 is involved in O2
.‐ generation and in the H2O2‐induced contraction in coronary VSM. (A, B) Effect of H2O2 (100 μM) and COX‐2 NS398 (1 μM) on O2
.‐ production in coronary artery (A) and in the myocardium (B) from OZR and LZR. (C, D) In endothelium‐denuded coronary arteries from LZR and OZR, the free radical scavenger tempol (30 μM) significantly reduced the contractile response to H2O2. (A, B) Results are expressed in counts min‐1 mg‐1 of tissue and represent the mean ± SEM of 8–20 animals. **P < 0.01 versus control before treatment; ##P < 0.01, ###P < 0.001 versus treated with H2O2; †P < 0.05, ††P < 0.01 versus LZR. (C, D) Results are expressed as a percentage of the KPSS‐induced contraction and represent the mean ± SEM from 5–7 arteries (1–2 per animal). *P < 0.05; **P < 0.01.