年龄与性别对大鼠收缩压和内皮源性血管活性物质昼夜节律的影响

Effects of age and gender on the circadian rhythm of systolic blood pressure and endothelial vasoactive substances in the rat

背景已有研究发现年龄与性别可以对血压的昼夜节律产生一定影响,但这些因素对内皮素1与一氧化氮这两种重要的血管活性物质昼夜节律的影响尚缺乏充分研究。目的以不同年龄和性别的大鼠为实验对象,探讨收缩压、血液中内皮素1和一氧化氮的昼夜节律特征。方法选择SD大鼠128只,分为4大组,每组32只,分别为:①成年雄性鼠,即10周龄雄性大鼠。②成年雌性鼠,即10周龄雌性大鼠。③老年雄性鼠,即96周龄雄性大鼠。④老年雌性鼠,即96周龄雌性大鼠。适应性饲养8周后,采用鼠尾测压仪测定大鼠的收缩压后,并分别于不同时间点(2:00、8:00、14:00、20:00)处死大鼠,每个时间点处死每组中8只大鼠。并留取血,分别采用放免法和硝酸还原法检测血液中内皮素1、一氧化氮的含量。结果①与成年雄、雌性鼠相比,老年雄、雌性鼠各时间段收缩压均明显升高(P<0.01),其血液中内皮素1、一氧化氮均降低(P<0.05)。与成年雄性鼠相比,成年雌性鼠的收缩压及血浆内皮素1降低,血清一氧化氮增加(P<0.05);与老年雄性鼠相比,老年雌性鼠收缩压无明显变化(P>0.05),血液中内皮素1、一氧化氮均降低(P<0.05)。②4组大鼠收缩压、内皮素1及一氧化氮曲线的基本昼夜节律均存在。与成年鼠相比,老年鼠的收缩压峰值位相明显不同。成年雄性鼠与成年雌性鼠的收缩压峰值相位不同;而老年雄性鼠和老年雌性鼠收缩压峰值相位无明显变化。在4组大鼠血液中内皮素1和一氧化氮的峰值相位发生不同程度的移位,昼夜节律特征发生了明显变化。结论不同年龄和性别对于大鼠收缩压、血液中内皮素1和一氧化氮的时间生物学特征有影响。

Background Age and gender may affect the circadian rhythm of blood pressure, but whether it exhibit the same effect on the circadian rhythms of endothelin-1（ET 1） and nitric oxide（NO） is unknown. Objective To investigate the circadian rhythm of systolic blood pressure and endothelial vasoactive substances in the rats of different age and gender. Methods One hundred and twenty-eight SD rats were divided into four groups： ①Adult male rats （10 weeks old）. ②Adult female rats （10 weeks old）. ③Older male rats （96 weeks old）. ④Older female rats（96 weeks old）. Rats were killed every 6 hours （at 2：00, 8：00, 14：00 and 20：00, respectively） by decapitation after systolic blood pressures （SBP） were measured. Plasma NO was measured by nitrate reductase technique. The level of plasma ET 1 was measured by radioimmunoassay. Results O SBP were markedly higher in older rats than in audlt rats（P〈0.01） , but the levels of plasma ET-i and NO were lower （P〈0.05）. Compared with adult male rats, SBP and the level of plasma ET-1 were decreased in adult female rats with the increased level of plasma NO（P〈0. 05）. Compared with older male rats, SBP of older female rats did not change significantly （P〈 0.05）, but the levels of plasma ET-1 and NO were lower（P〈01 05）. ②SBP and endothelial vasoaetive substances of four groups all showed the chronobiological features. There exists a difference in SBP peak phase between adult and older rats, also between adult male and female rats. However there was no difference between older male and female rats. The peak phase of endothelial vasoactive substances in every group showed signifieant shift. Conclusion Age and gender have impact on the chronobiological indices of systolic blood pressures and plasma ET-1 and NO.