同型半胱氨酸抑制培养的大鼠血管平滑肌细胞牛磺酸转运

Homocysteine Inhibits Taurine Transport in Rat Vascular Smooth Muscle Cells

为了研究同型半胱氨酸对血管平滑肌细胞牛磺酸转运的影响 ,采用培养的大鼠血管平滑肌细胞和3 H标记的牛磺酸 ,并测定血管平滑肌细胞牛磺酸转运。实验发现 ,同型半胱氨酸呈浓度依赖性抑制血管平滑肌细胞转运牛磺酸 ,1 0 0 μmol L和 50 0 μmol L同型半胱氨酸组血管平滑肌细胞牛磺酸转运的最大速率 (Vmax)较对照组分别降低 31 % (P <0 .0 5)和 51 % (P <0 .0 1 ) ,但组间Km值无显著差异 ;5mmol LH2 O2 亦抑制血管平滑肌细胞牛磺酸摄入 ,Vmax较对照组降低 48% (P <0 .0 1 ) ,但Km值增加 45 % (P <0 .0 1 ) ,其转运效率 (Vmax Km)较 50 0 μmol L同型半胱氨酸组更低 (3 .72± 0 .32比 5 .33± 0 .69,P <0 .0 1 )。 2 0mmol L牛磺酸和 50 0 μmol L同型半胱氨酸同时孵育 ,血管平滑肌细胞牛磺酸转运较 50 0 μmol L同型半胱氨酸组增加 ,Vmax增加 35 % (P <0 .0 5) ,两组间Km值亦无显著差异 ,转运效率增加 40 % (P <0 .0 5)。结果提示 ,同型半胱氨酸抑制血管平滑肌细胞牛磺酸转运 ,其机制不能用同型半胱氨酸产生过氧化物来解释 。

Aim To study effect of homocysteine (Hcy) on taurine uptake in cultured rat vascular smooth muscle cells (VSMC). Methods In cultured VSMC of rats, cellular 3 H taurine uptake were determined by 3 H taurine incubation. Taurine transport velocity was measured by radio ligand method. Results Hcy (10～500 μmol/L) could inhibit taurine transport in a dose dependent manner. As compared to control group, 100 and 500 μmol/L Hcy significantly decreased taurine transport. The maximal transport velocity (Vmax) decreased by 31% (P<0.05) and 51% (P<0.01), respectively. There were no significant changes in the Km value. 5 mmol/L H 2O 2 inhibited taurine transport. Vmax decreased by 48% (P<0.01), but Km value increased by 45% (P<0.01). Taurine could increase taurine transport that Hcy inhibited. Conclusions Hcy could inhibit taurine transport; The exogenous taurine could efficiently inhibit taurine transport dysfunction by Hcy induced.