Yamane M, Abe A
Department of Biochemistry, Tokyo Medical College, Japan.
Neurosci Lett. 1995 Nov 24;200(3):203-6. doi: 10.1016/0304-3940(95)12132-n.
The homogenate of a brain or liver obtained from a 1-55-day-old rat was incubated with NADPH and docosahexaenoic or arachidonic acid as the substrate. omega-Hydroxydocosahexaenoic or omega-hydroxyeicosatetraenoic acid from an incubation mixture of the homogenate was detected on a selected-ion monitoring chromatogram of reversed phase-HPLC-thermospray-mass spectrometry. omega-Hydroxylation activity in the brain homogenate considerably increased with growth up to 55 days. Activity in the liver homogenate decreased much with growth up to 55 days. omega-Hydroxylation activity in homogenates of rat brain gray matter, white matter, medula oblongata and cerebellum was much the same. omega-Hydroxylation activity of docosahexaenoic acid in rat brain homogenate was maximal at pH 7.5-8.0 in 50 mM Tris-HCl buffer and was inhibited by CO gas, metyrapone, ADP-Fe3+, heat treatment at 100 degrees C for 5 min and without NADPH. Based on these results, it is suggested that omega-hydroxylation activity is associated with cytochrome P-450 without NADPH-ADP-Fe(3+)-dependent lipid peroxidation, and the omega-hydroxylation system may be a metabolic pathway of the fatty acids in adult rat brain or neonatal rat liver. Since omega-hydroxyeicosatetraenoic acid produces relaxation of artery, it is suggested that blood flow changes in rat brain or liver with growth are caused by omega-hydroxylation activity changes in these organs with growth.
将取自1至55日龄大鼠的脑或肝脏匀浆与NADPH以及二十二碳六烯酸或花生四烯酸作为底物一起孵育。在反相高效液相色谱-热喷雾质谱的选择离子监测色谱图上检测匀浆孵育混合物中的ω-羟基二十二碳六烯酸或ω-羟基二十碳四烯酸。脑匀浆中的ω-羟基化活性随着生长直至55日龄而显著增加。肝脏匀浆中的活性随着生长直至55日龄而大幅下降。大鼠脑灰质、白质、延髓和小脑匀浆中的ω-羟基化活性大致相同。大鼠脑匀浆中二十二碳六烯酸的ω-羟基化活性在50 mM Tris-HCl缓冲液中pH 7.5 - 8.0时最大，并受到CO气体、甲吡酮、ADP-Fe3+、100℃热处理5分钟以及无NADPH的抑制。基于这些结果，提示ω-羟基化活性与细胞色素P-450相关，而不依赖于NADPH-ADP-Fe(3+)依赖性脂质过氧化，并且ω-羟基化系统可能是成年大鼠脑或新生大鼠肝脏中脂肪酸的代谢途径。由于ω-羟基二十碳四烯酸可使动脉舒张，提示大鼠脑或肝脏中随着生长的血流变化是由这些器官中随着生长的ω-羟基化活性变化所引起的。
