短、中期尾吊大鼠肾组织肾素-血管紧张素系统表达改变

Effects of Short-and Mid-term Tail Suspension on Renin-angiotensin System in Renal Tissue of Rat

目的探讨尾吊大鼠肾组织肾素-血管紧张素系统(renin angiotensin system,RAS)改变及与体液调节和肾功能变化的关系。方法采用尾吊1wk和4wk分别模拟短期和中期失重影响,应用反转录-聚合酶链式反应(RT-PCR)技术检测肾组织RAS各成分基因表达。结果与对照组相比,1wk尾吊大鼠肾组织肾素的mRNA表达显著升高;AGT,ACE,AT1a和AT1b的mRNA表达皆无显著改变。4wk尾吊大鼠肾组织肾素、AT1a和AT1b的mRNA表达无显著改变,AGT和ACE的mRNA表达皆显著降低。结论短期尾吊大鼠血浆肾素活性可能增强,而在中期时则恢复正常;此外,中期尾吊大鼠肾组织局部RAS活动水平下调。

Objective To explore changes of local renin-angiotensin system （RAS） in renal tissue of rat during short-and mid-term tail suspension, as well as their relations with humoral regulation and renal function induced by real or simulated weightlessness. Methods 1-and 4-week （wk） tail-suspended rat model were used to simulate short-and mid-term weightlessness, respectively. Reverse transcriptase polymerase chain reaction （RT-PCR） was carried out to examine the mRNA expression of components of local RAS in renal tissue. Results Except for angiotensin Ⅱ receptor type 2 （AT2）, all of the other components of local RAS, including angiotensinogen （AGT）, renin, angiotensin converting enzyme （ACE）, angiotensin Ⅱ receptor type la （AT1a）and angiotensin Ⅱ receptor type 1b （AT1b）, were found their expression in renal tissue of Sprague-Dawley rats. After 1 wk of tail suspension, mRNA expression of renin in renal tissue increased significantly （P 〈 0.01） as compared with control level. There were no significant differences in mRNA expression of AGT, ACE, AT1a and AT1b between control and 1-wk tail suspended rat. After a 4-wk tail suspension, as compared with control level, mRNA expression of renin, AT1a, and AT1b did not show any significant differences, but mRNA expression of AGT and ACE decreased significantly （P 〈 0.05 ,P 〈 0.01 ）. Conclusions The plasma renin activity （PRA） may increase in l wk, but return to normal level in 4 wk of tail-suspended rat. Besides, the local RAS tone may decline in renal tissue of 4-wk tail suspended rat.