关键词：受体，血管紧张素
摘要 目的 探讨老年大鼠心脏及肾脏中血管紧张素Ⅱ受体第1亚型(AT1)mRNA水平与受体密度的变化。 方法 采用逆转录-聚合酶链反应(RT-PCR)法测定3、12、24月龄Wistar大鼠心脏及肾脏AT1受体mRNA水平，用免疫组织化学法检测AT1受体密度的改变。 结果 正常大鼠肾脏中AT1受体mRNA的表达高于其在心脏中的表达。随年龄增长心脏AT1受体mRNA水平呈下降趋势，与3月龄组比较，12及24月龄组分别下降至3月龄组的87.0%±11.8%及70.8%±18.8%；而肾脏中未发现明显改变。免疫组织化学方法观察结果表明：24月龄大鼠阳性反应物面积下降，灰度无明显改变；在不同月龄大鼠肾脏中均未发现明显改变。 结论 随年龄增长心脏AT1受体mRNA水平下降、受体密度降低，肾脏AT1受体未发生明显改变，提示心脏功能更易受到老龄化的影响。
Senescent changes of angiotensin 1 receptor gene expression and receptor density in rat heart and kidney
Zhang Mei, Zhang Hong, Zhao Rongrui. Department of Physiology, Shanxi Medical University, Taiyuan 030001
Abstract Objective To study the age-related changes of angiotensin 1 (AT1) receptor mRNA level and receptor density in rats. Methods The mRNA level of AT1 receptor was measured with semi-quantitative RT-PCR technique and the AT1 receptor density was studied by immunohistochemical method. Results An aging associated decline of AT1 receptor mRNA level showed in rat heart. Compared with 3 months old rats, the mRNA level decreased to 87.0%±11.8% and 70.8%±18.8%(P<0.05) in 12 and 24 months old rats, respectively. However, the level of AT1 receptor mRNA in the kidney did not change significantly with age. Compared with 3 months old rats, the kidney mRNA level of 12 and 24 months old rats was 103.6%±14.9% and 90.7%±12.3% respectively (both P>0.05). In the immunohistochemical study by using image analysis system, it was shown that there was a similar tendency with the changes of mRNA level. In the heart, the positive object area of AT1 receptor decreased significantly in 24 months old rats, albeit the grey degree of positive objects showed no statistically significant changes. In the kidney, no changes were found either of the positive object area or of the grey degree. Conclusions The results that age-dependent decrease of AT1 receptor gene expression and of receptor density appeared in the heart but not in the kidney, indicate that the cardiac function is more susceptible to aging than the renal function.
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