1. The effects of mechanical clot removal during early surgery on pharmacological cerebrovascular reactivity after subarachnoid haemorrhage (SAH) were investigated in the monkey.
2. Contractions to potassium chloride, 5-hydroxytryptamine and noradrenaline in rings of proximal parts of middle cerebral arteries (MCP), surrounded with clot, and basilar arteries (BAP), far from the clot, were examined 7 days after SAH, in which an autologous blood clot was bilaterally placed around major cerebral arteries.
3. Compared with the sham-operated group, contractions in the clot removal groups at 48 and 72 h after SAH were reduced in MCP and enhanced in BAP.
4. These results suggest that divergent vascular contractility may occur according to the distance between artery and clot if the clot is removed later than 48 h after SAH.