Transcription profiling of rat cerebral arteries from rats after experimental SAH with the expression in cerebral vessels from sham operated animals

We have compared the gene-expression in cerebral arteries from rats after experimental SAH with the expression in cerebral vessels from sham operated animals. The model is well characterised (Prunell et al. 2003; Prunell et al. 2004) regarding the physiological changes but not regarding the gene expression pattern. Male Sprague-Dawley rats (350-400 g) were anaesthetized using 5% halothane (Halocarbon Laboratories, River Edge, New Jersey) in N2O/O2 (30:70). The rat was intubated and artificially ventilated with inhalation of 0.5-1.5% halothane in N2O/O2 (70:30) during the surgical procedure. The depth of anaesthesia was carefully monitored and the respiration checked by regularly withdrawing arterial blood samples for blood gas analysis (Radiometer, Copenhagen, Denmark). An arterial catheter to measure blood pressure was placed in the tail artery and a catheter to monitor intracranial pressure (ICP) was placed in the subocciptal membrane. At either side of the skull, 3 mm from the midline and 4 mm anteriorly from the bregma, holes were drilled through the skull bone down to dura mater (without perforation) allowing the placement of two laser-Doppler flow probes to measure CBF. Finally, a 27G blunt canula with side hole was introduced stereotactically 6.5 mm anterior to bregma in the midline at an angle of 30 degrees to the vertical. After 30 minutes of equilibration 250 ul blood was withdrawn from the tail catheter and injected intracranially at a pressure equal to the mean arterial blood pressure (80-100 mmHg). Subsequently the rat was kept under anaesthesia for another 60 minutes to allow recovery from the cerebral insult after which catheters were removed and the incisions closed. The rat was then revitalized and extubated. A subcutaneous injection of carprofen (4.0 mg/kg) (Pfizer, Denmark) was administered and the rat was hydrated subcutaneously using 40 ml isotonic sodium chloride at the end of the operation and at day one. During the period of observation the rat was monitored regularly, and if showing severe distress the animal was prematurely killed. In addition, a series of sham-operated rats were prepared. They went through the same procedure with the exception that no blood was injected intracisternally.

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