Abstract
In the previous studies, oxyhemoglobin or its allied polypeptides was found to be one of the most important causal factors of vasospasms. Haptoglobin has been found to be effective in releasing vasospasms in experimental models, but its beneficial effects in clinical cases were rather inconsistent. This is a report of our further studies, to find new spasmogenic substances in addition to Hb and to make the effects of Hp therapy more consistent and reliable.
In in vitro models vasoactivity of test substances was checked using a spirally cut strip of canine basilar artery. In the in vivo system, vasospasms were examined by cerebral angiography after the injection of the vasoactive substances directly into the chiasmatic cistern.
Breakdown products of the erythrocyte-membrane were found to be vasoactive in vitro. Its activity was markedly decreased after the procedure of lipid extraction and was partially blocked by the addition of serum albumin. However, less contractile response of the ghost breakdown products was observed in the in vivo experiments.
Fibrin degradation products (FDP), especially low molecular weight FDP (LMW FDP) demonstrated strong vasoactivity. Vasoactivity of FDP could be blocked by diphenhydramine. It was also found that FDP potentiated the vasocontractile action of Hb, and also augmented contraction induced by an aged erythrocyte-CSF mixture. When FDP was injected into the basal cistern in combination with hemoglobin, the marked vasospasms of a prolonged nature were demonstrated in the repeated angiograms. The degree of vasospasm thus produced was much greater than that induced by a single injection of hemoglobin. This vasospasm could be effectively released by the topical use of diphenhydramine and Hp. Gabexate mesilate(FOY) was moderately effective in releasing vasospasms even when it was administered intravenously. Systemic administration of gabexate mesilate and diphenhydramine was also effective for prolonged vasospasms induced by cisternal injection of autogeneous arterial blood in some cases. In the other cases additional topical application of Hp and diphenhydramine after removal of the subarachnoid hematoma by the transclival approach might be needed to release the vasospasm effectively.
