Cyclo-oxygenase inhibition by indomethacin and recirculation following cerebral ischemia

In this study we examined the effect of pretreatment with the cyclo-oxygenase inhibitor indomethacin (10 mg . kg-1) on local cerebral blood flow (DBF) in the immediate recirculation period following complete and incomplete ischemia. Ischemia of 15 min duration was induced in lightly anaesthetized and artificially ventilated rats, and local CBF was measured with a 14C-iodoantipyrine autoradiographic technique after recirculation periods of 5 min. Following complete ischemia indomethacin-treated animals showed a reduced incidence of perfusion defects of the "no-reflow" type. Perfused structures had somewhat higher flow rates than in untreated rats. A similar enhancement of immediate reflow was observed following incomplete ischemia provided that the structures in question had been severely ischemic. In structures that suffered only mild ischemia, the drug reduced postischemic CBF. It is concluded that, in the rat brain, cyclo-oxygenase inhibition does not curtail postischemic reactive hyperemia. Furthermore, the previously reported beneficial effect of indomethacin on brain circulation following complete ischemia seems to be due to an enhancement of immediate reflow, and to amelioration of an initial hindrance to reflow.