1. ¹Department of Neurosurgery, University Hospital Giessen–Marburg, Giessen, Germany
2. ²Department of Physiology, University of Giessen, Giessen, Germany

Correspondence: Dr MF Oertel, Department of Neurosurgery, University Hospital Giessen–Marburg, Klinikstrasse 29, Giessen 35385, Germany. E-mail: matthias.oertel@neuro.med.uni-giessen.de

Received 21 March 2008; Revised 1 July 2008; Accepted 1 July 2008; Published online 13 August 2008.

Abstract

Molecular mechanisms of cerebral vasospasm after subarachnoid hemorrhage (SAH) include specific modes of cell signaling like activation of nuclear factor (NF)-B and vascular cell adhesion molecules (VCAM)-1 expression. The study's hypothesis is that cisternal cerebral spinal fluid (CSF) from patients after SAH may cause Ca²⁺ oscillations which induce these modes of vascular inflammation in an in vitro model of human cerebral endothelial cells (HCECs). HCECs were incubated with cisternal CSF from 10 SAH patients with confirmed cerebral vasospasm. The CSF was collected on days 5 and 6 after hemorrhage. Cytosolic Ca²⁺ concentrations and cell contraction as an indicator of endothelial barrier function were examined by fura-2 microflurometry. Activation of NF-B and VCAM-1 expression were measured by immunocytochemistry. Incubation of HCEC with SAH-CSF provoked cytosolic Ca²⁺ oscillations (0.310.09 per min), cell contraction, NF-B activation, and VCAM-1 expression, whereas exposure to native CSF had no significant effect. When endoplasmic reticulum (ER) Ca²⁺-ATPase and ER inositol trisphosphate (IP3)-sensitive Ca²⁺ channels were blocked by thapsigargin or xestospongin, the frequency of the Ca²⁺ oscillations was reduced significantly. In analogy to the reduction of Ca²⁺ oscillation frequency, the blockers impaired HCEC contraction, NF-B activation, and VCAM-1 expression. Cisternal SAH-CSF induces cytosolic Ca²⁺ oscillations in HCEC that results in cellular constriction, NF-B activation, and VCAM-1 expression. The Ca²⁺ oscillations depend on the function of ER Ca²⁺-ATPase and IP3-sensitive Ca²⁺ channels.