隙缝连结在脑血管痉挛中的作用

Cerebral vasospasm(CVS) after subarachnoid hemorrhage(SAH) is one of the most serious, unsolved problems in neurosurgerical practice. But the mechanism how vasoactive agents, such as oxyhemoglobin(OxyHb) and ET-1 cause cerebral vascular smooth contraction is still unknown. Gap Junctions(GJ) are one of the structures directly connecting cells by which cells communicate each other. There are plenty of gap junction proteins(connexin,Cx) in vascular wall cells which are critical to the modulation of vasomotor tone. We first developed the study about the role of gap junctions in cerebral vasospasm, including: 1) to identify which types of connexins are expressed in the rabbit basilar arteries by using RT-PCR and immunoflorescence; 2) to know whether these types of connexins are upregulated by the self blood of the animals in rabbit two-hemorrhage model; 3) to observe the inhibitive effect of heptanol, the blocker of gap junctions, on the contraction of cerebral vascular rings caused by OxyHb(in vitro); 4) to investigate the therapeutic role of heptanol in cerebral vasospasm after two-hemorrhage model by the injection of the blocker into the carotid artery or the cisterna magna(in vivo). The results were: 1) There are abandon of Cx40、Cx45、Cx43 and Cx37 mRNA expression in the rabbit basilar arteries by using RT-PCR. Cx43 and Cx45 primarily appeared between endothelial and adventitial cells by using immunoflorescence, but not obviously between smooth muscle cells. Because other elastic arterial smooth muscle cells have plenty of Cx43, we deduce that the expression of connexins in the rabbit basilar arterial smooth muscle cells are different from others; 2) We successfully established the rabbit two-hemorrhage model with nearly 100% rate of cerebral vasospasm; 3) There are more connexins expressed after SAH, which indicated OxyHb may upregulate the expression of Cx in the rabbit basilar arteries; 4) The experiment in vitro showed that OxyHb can cause constantly constriction of arterial rings. The constriction can be obviously inhibited by heptaol with dose-response relationship; 5) Heptanol in vivo can reverse the blood-induced vasospasm, and suggest that this blocker injected into the cisterna magna or artery would be an effective treatment of vasospasm after acute SAH and chronic two-hemorrhage model. All these results are inspiring and indicate that gap junctions may play a pathophysiological role in CVS and heptanol has an effective treatment to the experimental animals. Our research prvoides a new way to explanation the mechanism of CVS and has a potential therapeutic role for the patients with vasospasm.

脑血管痉挛是神经科学急待解决的问题之一，缩血管物质如血红蛋白、内皮素等是如何引起脑血管平滑肌持续收缩的机理至今未明。隙缝连结能将血管内外的这些物质传向平滑肌或传导第二信使引起血管收缩。提示隙缝连结可能与脑血管痉挛的形成有关。本课题应用免疫组化、RT-PCR等技术研究隙缝连结在蛛网膜下腔出血后脑血管痉挛中的作用。