茶提取物预防离体大鼠血管对硝酸甘油耐受作用的研究

目的探讨茶提取物茶多酚和茶黄素预防离体大鼠血管对硝酸甘油耐受的作用。方法用硝酸甘油30μM预孵90min的方法诱导大鼠离体胸主动脉环对硝酸甘油产生耐受,用苯肾上腺素预收缩血管,通过organbath的方法观察茶提取物茶多酚和茶黄素处理与否对硝酸甘油舒张血管作用的影响。结果硝酸甘油预孵使血管对硝酸甘油的舒张反应显著减弱,pD2由对照组的8.21±0.09降低为耐受组的6.86±0.20（P〈0.05）;茶多酚和茶黄素预处理均使硝酸甘油耐受血管的舒张反应明显增强,pD2值分别为7.76±0.11和7.97±0.13,与耐受组相比均P〈0.05;各组Emax无显著变化。结论茶多酚和茶黄素预处理可预防离体大鼠血管发生硝酸甘油耐受。

Prevention of nitroglycerin tolerance of in vitro rat blood vessel by tea extract

Objective To investigate the preventive effect of tea polyphenols and theaflavin on the nitroglycerin tolerance of in vitro rat aorta.Methods Rat aortic rings were suspended in organ bath for the measurement of changes in isometric tension and nitroglycerin tolerance was acutely induced by preceding exposure for 90 min to 30 μM nitroglycerin.Concentration-response curves to nitroglycerin were obtained on aortic rings pre-contracted with phenylephrine.Results Pre-exposure of aortic rings with endothelium to nitroglycerin reduced the relaxations to nitroglycerin（pD2 values：8.21 ± 0.09 in control group vs 6.86 ± 0.20 in tolerance group,P0.05）.Treatment with tea polyphenols and theaflavin increased relaxation＇s response to nitroglycerin in tolerant aortic rings（pD2 values：7.76 ± 0.11 in tea polyphenols group and 7.97 ± 0.13 in theaflavin group vs 6.86 ± 0.20 in tolerance group,P0.05）.There is no significant difference in Emax between each group.Conclusion Nitroglycerin tolerance of in vitro aorta may be prevented by tea polyphenols and theaflavin.