4-anisyltetrazolium-blue and Brain-Ischemia

Focal ischaemia in the rat cerebral cortex was produced by means of a photochemically induced thrombosis of cerebral arteries. This was achieved by intravenous infusion of the photosensitive dye Rose Bengal and illumination of the skull with focused green light. Initial experiments justified the use of tetrazolium staining as an index of infarct damage. Using this technique it was demonstrated that chlormethiazole (200 mg/kg, i.p.) given 5 min post ischaemia markedly reduced the area of infarcted cortical tissue. A second experiment replicated this observation and showed that, in contrast, nimodipine (0.5 mg/kg, i.p.) given 5 min post infarct was without effect on infarct size. The pattern of Evans Blue extravasation indicated that the infarct developed over a 24-h period with the major damage occurring in the first 4.5 h. The spread of the infarct beyond the initial core of damage was decreased by an estimated value of almost 50% by injection of chlormethiazole (200 mg/kg, i.p.) 5 min after the light exposure. These data indicate that chlormethiazole is an effective drug in protecting against the effects of focal ischaemia in the rat and, taken with earlier observations that chlormethiazole protects against the effects of global ischaemia in the gerbil, suggest that the drug may be an effective treatment against the ischaemic cell death that can occur following a stroke or cardiac arrest.

Topics: Animals; Body Temperature; Brain Ischemia; Cerebral Infarction; Chlormethiazole; Evans Blue; Male; Nimodipine; Photochemistry; Rats; Tetrazolium Salts

This study examined the effects of permanent, unilateral cerebral artery occlusion on the somatosensory evoked potential (SEP) recorded from the ipsilateral cortex in the anaesthetised rat. Ten days after artery occlusion the SEP was absent in the majority of rats tested and in the remainder the wave amplitude was reduced compared to the potential recorded from the normal hemisphere but latency was unaffected. Histochemical staining with Tetrazolium for infarct size has shown that loss of the SEP correlated with ischaemic damage to the cortex. SEP recording can be used to assess the extent of cortical ischaemia in this small animal model.

Topics: Animals; Arterial Occlusive Diseases; Brain Ischemia; Cerebral Arteries; Chronic Disease; Evoked Potentials, Somatosensory; Female; Rats; Rats, Inbred Strains; Staining and Labeling; Tetrazolium Salts