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，也受有机渗透物的调节，如氨基酸、甲胺和多元醇。利用质子核磁共振波谱（^1H-NMR）技术，我们测量了大脑中动脉闭塞（不完全性局灶性缺血）和断头（完全性全脑缺血）后大鼠脑内有机渗透物的组织浓度。以总氨基酸、总甲胺和总多元醇的总和表示的总渗透物在局灶性缺血24小时显著降低（为对照组的58.7%，P=0.0025），而在断头后没有变化。局部缺血后（P<0.0001），而非断头后，脑组织含水量由对照组的77.9%增加到84.1% （P<0.0001）。提示脑有机渗透细胞参与局灶性脑缺血后水肿的形成过程。进一步阐明在脑缺血中调节这些有机渗透物的细胞机制，可能会促进对脑水肿病理生理学的更深入了解，并促进新的治疗措施的发展。

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.