LOCALIZATION OF IMMUNOREACTIVE FACTOR-VIII, NITRIC-OXIDE SYNTHASE, SUBSTANCE-P, ENDOTHELIN-1 AND 5-HYDROXYTRYPTAMINE IN HUMAN POSTMORTEM MIDDLE CEREBRAL-ARTERY

This pre-embedding electron-immunocytochemical study investigated the localisation of endothelial (type III) and neuronal (type I) isoforms of nitric oxide synthase, substance P, endothelin-1 and 5-hydroxytrypt amine in the human middle cerebral artery taken up to 40 h postmortem. To 'recover' from the anoxic period some of the vessels were incubate d in oxygenated Krebs solution prior to the immunoprocedure. At this l ong postmortem time, immunoreactivity to type III and type I nitric ox ide synthase, substance P, endothelin-1 and 5-hydroxytryptamine was fo und in a subpopulation of intact cells present in the vessel intima; i mmunoreactivity to type I nitric oxide synthase was also observed in a subpopulation of adventitial perivascular nerve fibres. Cultures of t he cells from the intima of the postmortem vessels showed that the cel ls were proliferating and positive immunoreactivity to factor VIII ide ntified them as endothelial cells. The results therefore indicate that even after up to 40 h postmortem, endothelium of human middle cerebra l artery is immunoreactive for a number of vasoactive agents and periv ascular nerve fibres show nitric oxide synthase immunoreactivity.