gms | German Medical Science

The delayed cerebral vasospasm after subarachnoid hemorrhage (SAH) is apparently a multifactorial process, including dysfunction of fibroblasts, smooth muscle cells and endothelium. The aim of the present study was to investigate whether cisternal ceobrospinal fluid is able to influence the endothelial cytosolic Ca²⁺ concentration after SAH.

As an experimental model HUVEC (human umbilical cord vein endothelial cells) were incubated with cisternal cerebrospinal fluid (CSF) of 8 patients with SAH. Four of these patients had cerebral vasospasm. In control experiments we used native CSF. HUVEC were loaded with the fluorescence Ca²⁺ indicator FURA-2. The emitted fluorescence light was collected with an inverted microscope attached to a video imaging system.

Incubation of HUVEC with SAH-CSF provoked cytosolic Ca²⁺ oscillations in 6 of 8 cases. After perfusion with CSF sampled from patients with cerebral vasospasm (n=4) endothelial Ca²⁺ oscillations appeared immediately in all cases. The oscillation frequency was 0,27±0,016 min^-1 (mean value±SEM; n=44 cells). In the presence of tapsigargin an inhibitor of endoplasmic reticulum (ER) Ca^2+--ATPase, the oscillations ceased in all cases. In further experiments the ER inositol-triphosphate (IP3) receptor gated Ca²⁺-channels were blocked by xestospongin and the ryanodine-dependent Ca²⁺-channels by rayanidine. Neither xestospongin nor ryanodine leads to a relevant reduction of the Ca²⁺ oscillations-frequency. In control experiments with native CSF no oscillations were observed.

Cisternal SAH-CSF, especially from patients with cerebral vasospasms, is able to induce endothelial cytosolic Ca²⁺ oscillations. These oscillations can be blocked by tapsigargin and are not influenced by IP3- and ryanodine-dependent Ca²⁺-channel activity. This indicates that SAH-CSF direct impairs ER Ca^2+--ATPase function possibly by attack of hydoxyl radicals on the ATP-binding site.