慢性低氧高二氧化碳大鼠右心室尾加压素Ⅱ受体的变化

Alteration of urotensin Ⅱ receptor in the right ventricular hypertrophy in rats induced by chronic hypoxia-hypercapnia

目的 :探讨慢性低氧高二氧化碳大鼠右心室肌浆膜尾加压素Ⅱ (UⅡ )受体的变化。方法 :在慢性低氧高二氧化碳肺动脉高压、右心室肥大的大鼠模型上 ,采用放射性配基结合法 ,测定不同低氧时间 (1w、2w、4w)右心室肌浆膜上UⅡ受体的结合率。结果 :慢性低氧高二氧化碳大鼠的肺动脉平均压 (mPAP)和右心室 (RV)与左心室加室间隔 (LV +S)重量比 (RV/LV +S)明显增高 (P <0 .0 1 ) ,1w组较正常对照组分别高 2 6 .2 %和 2 1 .6 % (P <0 .0 1 ) ,2w组又比 1w组分别高 2 2 .5 %和 1 4 .1 % (P <0 .0 1 ) ,2w组与 4w组差异有显著性。右心室肌浆膜UⅡ受体数目 (Bmax) ,1w组比正常对照组高 2 4 .4 % (P <0 .0 1 ) ,4w组又比 2w高 1 9.8% (P <0 .0 1 ) ,UⅡ受体亲和力 (Kd值 )各组间无差别 (P >0 .0 5)。结论 :慢性低氧高二氧化碳使大鼠右心室肌浆膜上UⅡ受体增加 ,且有随低氧时间延长而增加的趋势 。

Objective: To investigate the dynamic change of functional receptors for urotensin Ⅱ(UⅡ) in chronic hypoxia and hypercapnia induced-right ventricular hypertrophy in rat s. Methods: In the right ventricular hypertrophy of rats produced by chronic hypoxia-hyperc apnia,UⅡ binding sites in myocardial sarcolemma were determine d by radioligand assay at 1?2 and 4 weeks. Results: Mean pulmonary pressure(mPAP) and weight ratio of right ventricle to left ventri cle and septum(RV/LV+S) of hypoxia-hypercapnia 1 week group were 26.2% and 21.6 % highr respectively(P<0.01),compared with normal control g ro up. In 2-week group,mPAP and RV/LV+S were 22.5% and 14.1% higher respectively (P<0.01) than those in 1-week group.However,no difference was fo und between 2-week group and 4-week group(P>0.05). UⅡ recept ors (Bmax) of 1-week group were increased by 24.4%(P<0.01),comp ared with normal control group,and those of 4-week group increased by 19.8%(P<0.01),compared with 2-week group.No difference existed among each group in the affinity to UⅡ.Conclusion: The up-regulation of UⅡ receptor of mycardial sarcolemma in the rats chronical ly exposed to hypoxia and hypercapnia tend to increase as hopoxia and hypocap nia prolong which may be involved in the development of right ventricular hyper trophy.