银杏内酯B对大鼠中性白细胞花生四烯酸代谢酶和细胞内钙水平的影响

目的　观察银杏内酯B对大鼠中性白细胞花生四烯酸代谢酶及细胞内钙水平的影响。方法　反相高效液相色谱及Fura-2/AM荧光指示剂法。结果　银杏内酯B在0.1-10μmol·L^-1范围内，使花生四烯酸释放量降低10.9%-22.2%；0.1-50μmol·L^-1时，LTB₄和5-HETE生成量分别降低29.4%-88.6%和26.2%-89.3%；在0.1-100μmol·L^-1使PAF和fMLP刺激引起的细胞内游离钙浓度分别降低13.9%-51.4%和2.2%-36.6%。结论　银杏内酯B能抑制体外大鼠中性白细胞花生四烯酸代谢酶的活性及细胞内游离钙浓度的升高。

EFFECTS OF GINKGOLIDE B ON ARACHIDONIC ACID METABOLIZING ENZYMES AND LEVEL OF INTRACELLULAR CALCIUM IN RAT POLYMORPHONUCLEAR LEUKOCYTES

AIM: To investigate the effects of ginkgolide B on arachidonic acid (AA) metabolizing enzymes and the level of intracellular calcium in rat polymorphonuclear leukocytes. METHODS: Intracellular free calcium was quantitated by Fura-2 fluorescence technique. Phospholipase A2 (PLA2) activity was determined by incorporating 3H-arachidonic acid in leukocytes. 5-Lipoxygenase (5-LO) activity was evaluated by RP-HPLC. RESULTS: In comparison with control, ginkgolide B at final concentration of 0.1-10 mumol.L-1 inhibited A23187 induced AA release by 10.9%-22.2%; at final concentration of 0.1-50 mumol.L-1, ginkgolide B inhibited LTB4 and 5-HETE synthesis stimulated by PAF by 29.4%-88.8% and 26.2%-89.3% respectively. At the final concentration of 0.1-100 mumol.L-1, ginkgolide B decreased the rise of intracellular calcium level induced by pletelet activating factor (PAF) and N-formyl-methionine-leucine-phenglalanine (fMLP) by 13.9%-51.4% and 2.2%-36.6%, respectively. CONCLUSION: Ginkgolide B was found to significantly inhibit PLA2 and 5-LO activities, as well as the increase of the intracellular calcium induced by PAF.