Evidence for the presence of a vasoactive substance (possibly involved in the aetiology of cerebral arterial spasm) in cerebrospinal fluid from patients with subarachnoid haemorrhage.

Cerebrospinal fluid from patients with subarachnoid haemorrhage and cerebral arterial spasm contracted the isolated basilar artery and potentiated contractions produced by 5-hydroxytryptamine, noradrenaline, and six prostaglandins. The unidentified substance in cerebrospinal fluid probably plays a role in the aetiology of cerebral arterial spasm.