Parkinson Fiona E, Friesen Jessica, Krizanac-Bengez Ljiljana, Janigro Damir
Department of Pharmacology, University of Manitoba, A403, 753 McDermot Avenue, Winnipeg, MB R3E 0T6, Canada.
Brain Res. 2003 Aug 8;980(2):233-41. doi: 10.1016/s0006-8993(03)02980-9.
Extracellular adenosine is produced in brain during physiological and pathophysiological conditions. Once produced, this adenosine can undergo one or more of the following fates: it can interact with its receptors, it can be scavenged by astrocytes and/or neurons for ATP resynthesis, it can be transported across the blood-brain barrier and lost from the central nervous system, or it can be metabolized to inosine and hypoxanthine. The present study used a three-dimensional in vitro cell culture model of the rat blood-brain barrier, in which forebrain astrocytes and microvascular endothelial cells were cultured in cartridges containing multiple parallel polypropylene hollow fibers. Endothelial cells were cultured on the inner surfaces and astrocytes on the outer surfaces of these fibers. Growth medium was constantly perfused through the lumen of the fibers to mimic blood flow across endothelial cells in vivo. This co-culture system was used to examine the permeation of adenosine, and its metabolite inosine, from the astrocyte compartment to the endothelial cell compartment. Dipyridamole was added to the media perfusing the endothelial cell compartment to test whether it could decrease permeation of adenosine and inosine across the in vitro blood-brain barrier. Our results indicate that dipyridamole decreased permeation of total purines, especially inosine, across the barrier. Furthermore, permeation of fluorescein isothiocyanate-labeled albumin and radiolabeled sucrose, markers of the paracellular permeation pathway, were also decreased by dipyridamole. In conclusion, these data indicate that in addition to inhibiting nucleoside efflux across the barrier, dipyridamole can also improve blood-brain barrier function in this model.
细胞外腺苷在生理和病理生理条件下于大脑中产生。一旦产生，这种腺苷可经历以下一种或多种命运：它可与其受体相互作用，可被星形胶质细胞和/或神经元清除以进行ATP再合成，可穿过血脑屏障并从中枢神经系统中流失，或者可被代谢为肌苷和次黄嘌呤。本研究使用了大鼠血脑屏障的三维体外细胞培养模型，其中前脑星形胶质细胞和微血管内皮细胞在含有多个平行聚丙烯中空纤维的盒中培养。内皮细胞培养在这些纤维的内表面，星形胶质细胞培养在纤维的外表面。生长培养基持续灌注通过纤维内腔，以模拟体内血液流过内皮细胞的情况。该共培养系统用于检测腺苷及其代谢产物肌苷从星形胶质细胞区室到内皮细胞区室的渗透情况。将双嘧达莫添加到灌注内皮细胞区室的培养基中，以测试其是否能降低腺苷和肌苷穿过体外血脑屏障的渗透率。我们的结果表明，双嘧达莫降低了总嘌呤尤其是肌苷穿过屏障的渗透率。此外，双嘧达莫还降低了异硫氰酸荧光素标记的白蛋白和放射性标记的蔗糖（细胞旁渗透途径的标志物）的渗透率。总之，这些数据表明，双嘧达莫除了抑制核苷跨屏障流出外，在该模型中还可改善血脑屏障功能。
