No dantrolene protection in a dog model of complete cerebral ischaemia

Intracellular free calcium is believed to play a major role in the ischaemic cascade which leads to cell death. Calcium channel blockers, which in part inhibit the influx of extracellular calcium, have been shown to be neuroprotective in both complete and focal cerebral ischaemia models. Dantrolene, an agent used in the treatment of malignant hyperthermia, is known to inhibit the release of stored intracellular calcium. Assuming that reduced levels of intracellular free calcium would improve neurologic outcome, we studied the neuroprotective potential of dantrolene. A complete cerebral ischaemia model was used to examine ten anesthetized dogs. Five were given intravenous dantrolene and five were given equal volumes of saline prior to the ischaemic event. Simultaneous occlusion of the venae cavae and ascending aorta provided eleven minutes of complete cerebral ischaemia as monitored by electroencephalography. Arterial blood gases and serum glucose levels were drawn prior to ischaemia, 5 and 20 minutes post-ischaemia, and following extubation. Forty-eight hours following the ischaemic event, neurologic outcomes were scored. No significant differences were observed between the two groups. All ten dogs had equally significant increases in serum glucose levels at 5 and 20 minutes post-ischaemia. The average neurologic outcome of the five dantrolene-treated dogs equalled the average of the five controls. These results suggest that dantrolene, alone, is not neuroprotective during complete cerebral ischaemia.