Vasoconstrictive effects of human post-hemorrhagic cerebrospinal fluid on cat pial arterioles in situ.

Cat cortical arterioles were exposed in vivo to cerebrospinal fluid (CSF) from four patients with subarachnoid hemorrhage (SAH) due to a ruptured intracranial aneurysm. Pial arteriolar caliber was measured by the television image-splitting technique. There was a consistent vasoconstrictive response to CSF. This effect could be ascribed neither to the pH of the CSF nor to the potassium concentration. The vasoconstriction, which was more pronounced with decreasing arteriolar caliber, could be resolved by the perivascular application of nifedipine.