Effects of partial blood replacement with pyridoxalated hemoglobin polyoxyethylene conjugate solution on transient cerebral ischemia in gerbil

Blood components were reported to be aggravating factors of ischemic cerebral injury. We previously reported that a partial blood replacement with Fluosol DA reduced ischemic neuronal injury. The purpose of this study is to elucidate whether pyridoxalated hemoglobin polyoxyethylene conjugate solution (PHP) exerts neuro-protective effects against cerebral ischemia. Methods: 38 adult male gerbils were divided into 4 groups, such as normal group without ischemia or treatment, PHP group undergoing an exchanging blood transfusion with 5.0 ml PHP, ischemia group undergoing 5-min forebrain ischemia, and PHP-ischemia group with 5.0 mi PHP partial blood replacement prior to B-min forebrain ischemia. Cerebral injury was assessed 7 days after treatment. In another group, effects of PHP on blood nitric oxide (NO) and cerebral blood flow (CBF) were studied. Results: CA1 cell density was 140-2/mm in normal group and 142-5 /mm in PHP group. The cell density was markedly reduced to 38-13 in ischemia group. The cell density was further reduced 27-10/mm in PHP-ischemia group. PHP was found to have a potent NO scavenger action and reduce CBF. Conclusion: Partial blood replacement with PHP prior to ischemia may cause cerebral vasoconstriction due to NO scavenger action and may worsen ischemic injury.