Nag S, Robertson D M, Dinsdale H B
Am J Pathol. 1982 Jun;107(3):336-41.
Lanthanum, an electron-dense tracer, has been used extensively in the study of the structure of cell junctions. The present study was undertaken to determine whether the interendothelial junctions of normal intracerebral arterioles allow passage of lanthanum and to document the alterations occurring in these structures in acute hypertension. Perfusion of lanthanum for 12-40 minutes in control animals resulted in passage of tracer into arteriolar walls and into the extracellular compartment of the surrounding brain. The two principal mechanisms associated with tracer extravasation into the brain were diffuse passage through endothelial cytoplasm and through interendothelial spaces bypassing tight junctions. The latter finding has not been previously reported in normal cerebral arterioles and suggests that the tight junctions of these vessels are different from those of capillaries and consist of a meshwork of closely arranged maculae occludentes rather than complete circumferential occluding bands as was previously believed. Hypertensive animals showed accelerated passage of lanthanum, it being demonstrable not only in arteriolar walls but in capillary and venular walls and the surrounding neuropil after only 5 minutes of circulation. Passage of tracer through vessel walls occurred by the same routes as in control. In addition, increased numbers of pinocytotic vesicles were observed in the endothelium, confirming our previous studies that increased vesicular transport occurs in cerebral arteriolar endothelium in acute hypertension.
镧是一种电子致密示踪剂，已被广泛用于细胞连接结构的研究。本研究旨在确定正常脑内小动脉的内皮间连接是否允许镧通过，并记录急性高血压时这些结构发生的改变。在对照动物中灌注镧12 - 40分钟，导致示踪剂进入小动脉壁和周围脑组织的细胞外间隙。与示踪剂渗入脑内相关的两个主要机制是通过内皮细胞质的弥散性通过以及通过绕过紧密连接的内皮间间隙。后一发现此前在正常脑内小动脉中未见报道，提示这些血管的紧密连接不同于毛细血管的紧密连接，由紧密排列的闭锁小带网络组成，而非如先前认为的完整的环周闭锁带。高血压动物显示镧的通过加速，在循环仅5分钟后，不仅在小动脉壁，而且在毛细血管和小静脉壁以及周围神经纤维网中均可证实。示踪剂通过血管壁的途径与对照相同。此外，在内皮细胞中观察到吞饮小泡数量增加，证实了我们先前的研究，即在急性高血压时脑内小动脉内皮细胞中囊泡转运增加。
