Abstract
It was previously proposed that spasmogenic activity of oxyhemoglobin was stronger than that of methemoglobin and that oxyhemoglobin induced marked and continuous vasospasms on the exposed basilar artery in the cat. Therefore, oxyhemoglobin may be one of the most important spasmogenic substances following subarachnoid hemorrhages. It was also reported that, due to autoxidation, oxyhemoglobin produced superoxide, and that lipid peroxidation induced by superoxide with an Fe-complex was inhibited by superoxide dismutase, catalase, 1, 4-diazabicyclo [2, 2, 2] octane (DABCO), etc.
In this experiment, the spasmogenic activity of oxyhemoglobin on the exposed basilar artery was reduced to that of methemoglobin by superoxide dismutase, catalase and DABCO. On the other hand, methemoglobin induced marked contraction of the arteries after the xanthine oxidase system, which is believed to be a superoxide producing system, was injected into the subarachnoid space together with EDTA-Fe and FeCl3. The authors have therefore concluded that the strong spasmogenic activity of oxyhemoglobin is due to a change in reactivity of the artery which is affected by lipid peroxidation, induced by superoxide generated by autoxidation of oxyhemoglobin, on the cellular membrane of nerve-endings or smooth muscle of the artery.
