Nitric oxide is a major mediator in reactive hyperaemia evoked by a brief coronary occlusion in the guinea pig heart.

In the isolated perfused guinea pig heart coronary occlusion lasting 1-5 s is followed by reactive hyperaemia which is inhibited by 91-100% after pretreatment with a NO synthase inhibitor, NG-nitro-L-arginine (100 microM). Neither indomethacin (5 microM) nor 8-phenyltheophylline (10 microM) influences these responses. Therefore, the brief cardiac reactive hyperaemia seems to be predominantly if not entirely mediated by nitric oxide (NO).