THE NO-REFLOW PHENOMENON IS A POSTMORTEM ARTIFACT

Post-ischemic reperfusion impairment, ("no-reflow phenomenon"), was st udied in rats subjected to 8-30 minutes of global brain ischemia. Duri ng ischemia, rapid and complete loss of cerebral blood flow, EEG and P -31-high energy phosphates (ATP/PCr) was observed. Brain intravascular perfusion defects were examined by injecting carbon black intravenous ly in a group of rats with stable cardiopulmonary function and in anot her group subjected to rapid thoracotomy and intraarterial infusion of the carbon marker. Results indicate that global brain ischemic or non -ischemic control rats given intraarterial carbon black after thoracot omy had varying degrees of vessel filling defects in brain resulting i n "pale tissue areas" suggestive of impaired perfusion (no-reflow). Al l rats given carbon black intravenously whether global brain ischemic or not, showed normal cerebrovascular filling of the carbon black and absence of "pale tissue areas". In addition, post-ischemic cerebral re perfusion following 8-30 minutes global brain ischemia can reverse neu roelectric, energy metabolite and cerebral blood flow loss in rats who se cardiopulmonary function is not compromised. These findings indicat e that the "no-reflow phenomenon" is an agonal or post-mortem artifact observed in the presence of cardiopulmonary failure.