牛磺酸对次氯酸诱导的大鼠肝细胞核核苷三磷酸酶损伤的保护作用

目的探讨牛磺酸对次氯酸(hypochlorous acid,HOCl)诱导的大鼠肝细胞核核苷三磷酸酶(NTPase)损伤的保护作用。方法体外分离大鼠肝细胞核,用HOCl单独或与牛磺酸共同孵育,分别以ATP和GTP作底物检测核NTPase的活性。结果ATP和GTP作底物时,HOCl(1×10^-9～5×10^-6 mol·L^-1)以浓度依赖的方式抑制NTPase活性。牛磺酸(1×10^-6～1×10^-4 mol·L^-1)可显著拮抗HOCl(1×10^-6 mol·L^-1)导致的NTPase活性降低。另外,牛磺酸(1×10^-6～1×10^-4 mol·L^-1)单独孵育肝细胞核,对NTPase有轻度刺激作用。结论牛磺酸可浓度依赖地拮抗HOCl诱导的肝细胞核NTPase活性下降,此作用可能是其保护机制之一。

Taurine protects rat hepatic nuclear nucleoside triphosphatase from hypochlorous-induced suppression

Aim Export of mRNA from nucleoplasmic space via the nuclear pore complex requires nuclear nucleoside triphosphatase (NTPase) activation. It is widely believed that taurine plays important role in protecting cells from toxic injury by functioning as an antioxidant. To investigate whether taurine can directly protect nuclei NTPase from HOCl induced damage, the effects of taurine on NTPase due to incubation with HOCl were studied. Methods Isolated hepatic nuclei from rat liver were exposed to HOCl with or without taurine. The NTPase activities on nuclei were assayed using ATP and GTP as substrates. Results Incubation of rat hepatic nuclei with HOCl (1×10^{-9-5×10-6 mol·L-1) resulted in a concentration dependent decrease in nuclear NTPase activity (P<0.01). The reduction of NTPase activities induced by HOCl (1×10-6 mol·L-1) was antagonized by taurine from the very low concentration of 1×10-6 mol·L-1 (for ATP and GTP as substrates) (P<0.01). In incubating the nuclei with HOCl (1×10-6 mol·L-1) and taurine (5×10-4 mol·L-1), the nuclear NTPase activities reached (102±14) nmol·mg-1(protein)·10 min-1 (for ATP as substrate) and (133±12) nmol·mg-1(protein)·10 min-1 (for GTP as substrate), which showed significant differences from that of incubating the nuclei with HOCl alone ［(44±5) and (36±4) nmol·mg-1(protein)·10 min-1］ (P<0.01). In addition, incubation of hepatic nuclei with taurine (1×10-6-1×10-4 mol·L-1) slightly increased the nuclear NTPase activity, as compared with that of the control group (P<0.01), indicating that taurine itself showed NTPase-stimulating effect. Conclusion These data demonstrate that taurine antagonistically attenuated the toxicity of HOCl to the NTPase, indicating that nuclear NTPase would be one of the favorable targets of OCl- and taurine protects nuclear NTPase.}