Analysis of the changes in brain organic osmolytes in cerebral ischemia

细胞体积不仅受无机离子的调节，还受有机渗透调节剂的调节，如氨基酸、甲胺和多元醇(多元醇)。采用质子核磁共振波谱技术，测定了大鼠大脑中动脉闭塞(不完全性局灶性缺血)和断头后(完全性全脑缺血)脑组织中有机渗透压物质的浓度。用总氨基酸、总甲胺和总多元醇表示的总渗透压在缺血后24小时显著下降(为对照组的58.7%，P=0.0025)，而断头后无明显变化。局灶性脑缺血(P&lt；0.0001)后脑组织含水量由对照组的77.9%增加到84.1%，断头后未见明显变化。提示脑有机渗透压参与了大鼠局灶性脑缺血后脑水肿的形成过程。进一步阐明脑缺血时调节这些有机渗透调节物质的细胞机制可能有助于更好地了解脑水肿的病理生理机制以及开发新的治疗方法。

The cell volume is regulated not only by inorganic ions, but also by organic osmolytes, such as amino acids, methylamines, and polyhydric alcohols (polyols). Using proton nuclear magnetic resonance spectroscopy (^1H-NMR), we measured the tissue concentrations of those organic osmolytes in the rat brain after middle cerebral artery occlusion (incomplete focal ischemia) or after decapitation (complete global ischemia). The total osmolytes expressed as a sum of total amino acids, total methylamines, and total polyols were significantly decreased at 24 hours of focal ischemia (58.7% of control value, P=0.0025) whereas they were not changed following decapitation. The water content was increased from control value of 77.9% to 84.1% after focal ischemia (P<0.0001) bit not after decapitation. These results suggested that the brain organic osmolytes are involved in the process of edema formation following focal cerebral ischemia. Further elucidation of the cellular mechanisms regulating these organic osmolytes in cerebral ischemia may promote greater understanding of pathophysiology of brain edema as well as the development of novel measures of treatment.