Arachidonic acid and acetylcholine induced relaxation of bovine coronary artery: effect of indomethacin and methylene blue.

Endothelial intact bovine coronary artery (BCA) rings precontracted with U46619 relax to acetylcholine (Ach) and arachidonic acid (AA). Relaxation to Ach is blocked by atropine. In an attempt to elucidate the mechanisms of these responses, we found that preincubation with methylene blue, an inhibitor of soluble guanylate cyclase activity, inhibited both Ach and AA induced relaxation. Preincubation with indomethacin had no effect on Ach induced relaxation, but partially inhibited the relaxation of endothelial intact BCA rings to AA.