大鼠心脏α1-肾上腺素受体和血管紧张素Ⅱ受体亚型mRNA水平的增龄改变

Changes in mRNA levels of cardiac α1- adrenergic receptor and angiotensin Ⅱ receptor subtypes with aging in rats

目的从受体信使RNA（messenger RNA，mRNA）水甲研究了心脏α1肾上腺素受体（α1-AR）亚型和血管紧张素Ⅱ受体（ATR）亚型在大鼠增龄过程中表达水平的变化。方法采用半定量逆转录聚合酶链反应（semiquantitative reverse transcription polymerase chain reaction，RT～PCR）分别对3月龄（青年）、12月龄（中年）、18月龄（老年前期）和24月龄（老年）Wistar大鼠左心室的mRNA水平进行测定。结果α1A-AR随增龄逐渐下调，各年龄组的表达水平分别为0．71±0．06、0．29±0．06、0．23±0．03、0．12±0．04。α1D-AR在中老年前期下调。各年龄组的表达水平分别为0．52±0．05、0．41±0．03、0．24±0．11、0．27±0．08。α1B-AR的表达未随增龄而变化。AT1R在老年组出现明显上凋，各年龄组的表达水平分别为0．60±0．14、0．58±0．12、0．68±0．10、1．09±0．14。AT2R的表达水平在增龄过程中无明显变化。结论α1-AR亚型和ATR亚型的表达水平随年龄增长出现了明显改变，这可能是心脏在衰老过程中产生的适应性反应，并且对维持哀老心脏的生理功能具有重要意义。

Objective To examine the expression levels of α1-adrenergic receptor（α1-AR）and angiotensinⅡ receptor（ATR） subtypes in left ventricle of rats from adolescent age, middle age, presenium to senium. Methods Semiquantitative reverse transcription polymerase chain reaction （RT-PCR） was used to quantitate the messenger RNA （mRNA） of α1-AR and ATR subtypes in left ventricle in Wistar rats aged 3 months （adolescent age）, 12 months （middle age）, 18 months （presenium） and 24 months （senium）. Results The expression of α1-A-AR mRNA was decreased gradually with aging, and the gent expression of α1D-AR was repressed in middle age and presenium, while the expression of α1B-AR mRNA remained unchanged during senescence. Cardiac AT1R expression was not affected by aging from adolescent age to presenium, but exhibited a remarkable up- regulation in senium. There was no significant discrepancies of cardiac AT2R expression among the four different age groups. Conclusions The results suggest that there are considerable changes in mRNA levels of cardiac α1-AR and ATR subtypes with aging. The change of cardiac α1-AR and ATR expression during aging is a protective response for senescence and has an important significance in maintaining normal physiological functions of heart.