Loss of CO2-induced distensibility in cerebral arteries with chronic hypertension or vasospasm after subarachnoid hemorrhage.

We developed a rat cerebral angiography system using monochromatic synchrotron radiation X-rays at SPring-8, a third generation synchrotron radiation facility. Using new technique, we assessed the distensibility of major trunk arteries after subarachnoid hemorrhage (SAH) in normotensive and hypertensive rats. Twenty-five adult Wistar Kyoto rats (WKY) and fourteen stroke-prone spontaneously hypertensive rats (SHR) were prepared SAH by double hemorrhage injection method into cisterna magna. Angiography was performed on day 7 and was repeated three times in each rat before and after loading of hypercapnia at 100-120 mmHg of PaCO2. The diameters of major trunk vessels were assessed. Light microscopic observation of artery lumen and wall were also performed. Angiographical vasospasm was demonstrated in basilar artery in WKY with 66 % reduction in diameter of control. In ICA and other major trunk in WKY and all the arteries in SHR did not demonstrate vasospasm. SHA resulted in loss of hypercapnia-induced distention in BA of WKY. In SHR, the distensibility was impaired regardless of hemorrhage. Histological study demonstrated basilar artery in WKY thickened at 184 % after SAH and became similar to non-hemorrhagic SHR. ICA in WKY and both BA and ICA in SHR were unchanged in wall thickness before and after SAH. High quality angiography demonstrated deteriorated distensibility in chronic hypertension or SAH-induced spastic vessels.