Apoptosis in Basilar Endothelial Cells in a Canine Double Hemorrhage Model
Cerebral vasospasm after subarachnoid hemorrhage (SAH) is a combination of prolonged contraction and vessel remodeling that may lead to cerebral ischemia or infarction [2 ]. Morphological studies of cerebral arteries affected by vasospasm often show exten
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Apoptosis in Basilar Endothelial Cells in a Canine Double Hemorrhage Model A. Y. Zubkovt, R. E. Tibbst, B. Clower 2 , K. Ogiharat, K. Aokit, and J. H. Zhang! 1 Department 2
of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi, USA Department of Anatomy, University of Mississippi Medical Center, Jackson, Mississippi, USA
Introduction Cerebral vasospasm after subarachnoid hemorrhage (SAH) is a combination of prolonged contraction and vessel remodeling that may lead to cerebral ischemia or infarction [2]. Morphological studies of cerebral arteries affected by vasospasm often show extensive necrosis of smooth-muscle cells [1] as well as desquamation and dystrophy of endothelial cells [7, 11]. The actual mechanisms of cellular death following cerebral vasospasm are not known. Recent studies of post-SAH vasospasm in this laboratory strongly suggest that endothelial cells may be dying through apoptotic pathways [8, 10]. The dog double hemorrhage method, an established model for inducing vasospasm, was used in this study to investigate the time course of apoptotic changes in endothelial cells. Keywords: Apoptosis; endothelium; experimental subarachnoid haemorrhage.
Materials and Methods Dog Double Hemorrhage Model This study utilizes a double hemorrhage dog model previously described by Varsos et al. [9]. The first SAH was considered as day O. Two days later animals underwent a second SAH (day 2 SAH). The dogs were divided into three groups and were sacrificed (four per period) on days 3, 5, and 7, respectively. As stated above a second angiogram was performed on dogs just prior to their sacrifice. Three dogs were not exposed to SAH and served as controls for vessel pathology studies. Animals were sacrificed by an overdose of pentobarbital (120 mg/kg).
Morphological Studies Brains were immediately removed, and the circle of Willis, still attached to the brain stem, was quickly perfused with 2% glutaraldehyde. After processing, the samples were examined with a LEO
906 (Leo, Thoenwood, NY) transmission electron microscope (TEM). Data Analysis The angiographic data is expressed as the mean ± the standard error of the mean. Statistical differences between the control and other groups were compared using a one-way analysis of variance (ANOVA), and then, if significant variance was found, the TukeyKramer multiple comparison procedure. A probability value (P) of less than 0.05 was considered statistically significant.
Results
Angiographic Changes of the Basilar Arteries on Days 3-7 All four dogs developed mild vasospasm on day 3 with residual diameter of 80.8 ± 13.5%, which represents a 20% reduction in luminal size. On day 5, a moderate degree of vasospasm was observed, with residual diameter of 67.3 ± 6.4%, which represents a 33% reduction in luminal size. A severe vasospasm was obtained on day 7 with residual diameter of 53.4 ± 5.5%, representing a 47% reduction in luminal size.
Morphology of Normal Basilar Arteries The normal basilar artery consists of three layers, the intima, the media, and
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