Sciotti V M, Van Wylen D G
Department of Pathology, School of Medicine and Biomedical Sciences, State University of New York, Buffalo 14215.
J Cereb Blood Flow Metab. 1993 Mar;13(2):208-13. doi: 10.1038/jcbfm.1993.25.
The purpose of this study was to determine the effects of homocysteine, which consumes intracellular adenosine via formation of S-adenosylhomocysteine, on interstitial fluid (ISF) adenosine and cerebral blood flow (CBF) before, during, and after cerebral ischemia. Microdialysis probes, used to measure local CBF (H2 clearance) and to sample ISF, were implanted bilaterally into the caudate nucleus of halothane-anesthetized rats (n = 8). L-Homocysteine thiolactone was administered locally via one of the probes. Animals were exposed to 20 min of ischemia, induced by bilateral carotid occlusion plus hemorrhage to an arterial blood pressure of 50 mm Hg, followed by 60 min of reperfusion. Before ischemia, CBF and dialysate adenosine were decreased with homocysteine. During ischemia and early reperfusion, dialysate purine metabolites increased on both sides of the brain; however, the ischemia-induced increase in adenosine was attenuated on the side of local homocysteine. CBF was lower on the side of homocysteine throughout reperfusion. These data demonstrate that homocysteine (a) decreases basal ISF adenosine and CBF, (b) attenuates the increase in dialysate adenosine during ischemia, and (c) reduces hyperemia during early reperfusion.
本研究的目的是确定同型半胱氨酸（通过形成S-腺苷同型半胱氨酸消耗细胞内腺苷）在脑缺血前、缺血期间和缺血后对间质液（ISF）腺苷和脑血流量（CBF）的影响。将用于测量局部CBF（H2清除率）和采集ISF的微透析探针双侧植入氟烷麻醉大鼠（n = 8）的尾状核。通过其中一个探针局部给予L-同型半胱氨酸硫内酯。动物经历20分钟的缺血，通过双侧颈动脉闭塞加出血诱导动脉血压降至50 mmHg，随后进行60分钟的再灌注。缺血前，同型半胱氨酸使CBF和透析液腺苷降低。在缺血和早期再灌注期间，脑两侧的透析液嘌呤代谢产物均增加；然而，局部同型半胱氨酸侧缺血诱导的腺苷增加减弱。在整个再灌注过程中，同型半胱氨酸侧的CBF较低。这些数据表明，同型半胱氨酸（a）降低基础ISF腺苷和CBF，（b）减弱缺血期间透析液腺苷的增加，以及（c）减少早期再灌注期间的充血。
