Identification and quantification of the hydroxyeicosatetraenoic acids, 20-HETE and 12-HETE, in the cerebrospinal fluid after subarachnoid hemorrhage

Abstract

Purpose: The monohydroxylated metabolite of arachidonic acid, 20-hydroxyeicosatetraenoic acid (20-HETE), is a potent vasoconstrictor of cerebral microvessels. 20-HETE formation is substantially elevated in the cerebral spinal fluid (CSF) in the rat subarachnoid hemorrhage (SAH) model. The presence of 20-HETE in human CSF has not been demonstrated. Therefore, it was the purpose of this study to determine if HETE metabolites are present in human CSF after SAH. Methods: CSF samples were collected daily from four SAH patients over 15 days. HETE metabolites were separated by HPLC with identification by ion-trap MS/MS and quantification via single quadrupole MS operating in negative single ion monitoring mode. Results: Two major metabolites were identified as 12-HETE and 20-HETE. 20-HETE maximal concentrations were 2.9 and 0.7 ng/ml at ∼70 h in the two patients with symptomatic cerebral vasospasm (SV) after SAH. Concentrations of 12-HETE in these patients peaked at 21.9 ng/ml and 2.8 ng/ml. Concentrations of 20-HETE and 12-HETE were non-detectible in the majority of the samples obtained from two matched SAH patients without SV. Conclusions: This study is the first to demonstrate that 20-HETE and 12-HETE are present in the CSF of SAH patients at physiologically relevant concentrations. Based on this information future prospective studies will allow for the delineation of the role of these metabolites in the pathogenesis of SAH.