牛磺酸对大鼠胸主动脉的舒张作用及其机制的研究

目的研究牛磺酸舒血管作用的可能机制。方法记录苯肾上腺素(PE)和KCl预收缩的离体大鼠主动脉环张力变化,观察牛磺酸的舒血管作用及不同工具药对其作用的影响。结果牛磺酸(20~80mmol.L-1)对PE(1μmol.L-1)或KCl(60mmol.L-1)预收缩的大鼠主动脉环均有非内皮依赖的、浓度依赖性的舒张作用。在内皮完整的血管环,左旋硝基精氨酸甲酯(0.1mmol.L-1)对牛磺酸的舒血管作用无明显影响;β-丙氨酸(60mmol.L-1)在PE预收缩的血管环增强牛磺酸的舒血管作用,而在KCl预收缩的血管环则降低牛磺酸的舒血管作用;在KCl预收缩基础上,钾通道阻断剂格列本脲(10μmol.L-1)和四乙胺(10mmol.L-1)明显抑制牛磺酸的舒血管作用,而4-氨基吡啶(1mmol.L-1)和BaCl2(1mmol.L-1)无影响。结论牛磺酸有浓度依赖性的血管舒张作用,此作用不依赖血管内皮,可能与其跨细胞膜转运有关,可能有钙依赖性钾通道和ATP敏感性钾通道的参与。

Vasodilative effect and mechanism of taurine on thoracic aorta of rats

AIM To investigate the vasodilative roles and the possible mechanisms of taurine on thoracic aorta of rats. METHODSIsotonic tension of thoracic aortic rings precontracted by phenylephrine (PE, 1 μmol·L^-1) or KCl (60 mmol·L^-1) was recorded. The vasorelaxing action of taurine and the influence of various drugs on it were observed in the rings with endothelium intact or endothelium denuded. RESULTS Taurine (20-80 mmol·L^-1) caused concentration-dependent relaxation in thoracic aortas with or without endothelium, and there was no significant difference between them. N^G-nitro-L-arginine methyl ester (0.1 mmol ·L^-1) had no effect on the vasorelaxing action of taurine on thoracic aortas precontracted by PE or KCl. β-Alanine (60 mmol·L^-1) diminished the vasorelaxing action of taurine in KCl- precontracted rings, but enhanced the action in PE-precontracted rings. Tetraethylamine, an antagonist of calcium activated potassium channels (KB_Ca), and glibenclamide, an antagonist of ATP sensitive potassium channels (K_ATP) attenuated the vasorelaxing effect of taurine, but 4-aminopyridine and BaCl₂ had no significant effect on the vasorelaxing action of taurine. CONCLUSION The vasorelaxing action of taurine is endothelium-independent and associated with taurine transmembrane transportation; KB_Ca and K_ATP may be involved in the action of taurine.