Changes in renin and atrial natriuretic polypeptude mRNA levels.

研究了不同钠摄入量大鼠和自发性高血压大鼠(SHR)肾素、血管紧张素原和心钠素(ANP)基因的表达。用放射密度法检测血管紧张素原和心钠素的信使核糖核酸(信使RNA)。用大鼠肾素基因最后一个外显子的760个碱基对的Rsa I片段作为探针进行放射免疫测定，以测定肾脏肾素基因的表达。在高钠状态下，血浆肾素浓度(PRC)、肾脏肾素浓度(RRC)和肾脏肾素mRNA分别下降了88%、90%和75%。在低钠状态下，PRC、RRC和肾素mRNA分别增加了17倍、2.5倍和4.5倍。在钠耗竭时应用卡托普利，RRC和肾素mRNA分别增加144倍和17.1倍，RRC增加4.2倍。肝脏和肾脏血管紧张素原基因表达水平在高钠状态下降低，在低钠状态下升高。卡托普利治疗使两个器官中血管紧张素原的mRNA减少了大约一半。与高钠状态相比，低钠状态下血浆ANP和ANP mRNA降低，而心房ANP含量在低钠和高钠状态下均无变化。这些结果表明钠摄入量影响肾素、血管紧张素原和心钠素基因的表达。在4、8、12和16周龄的SHR和Wistar京都大鼠(SHR)中，SHR的PRA和PAC与WKY的PRA和PAC没有差异。SHR和WKY大鼠肾脏肾素mRNA水平和心房ANP mRNA水平无明显变化。提示肾肾素和心房心钠素可能与血压升高无关。

The expressions of the renin, angiotensinogen and atrial natriuretic polypeptide (ANP) genes were studied in rats with varying sodium intakes and the spontaneously hypertensive rats (SHR). Messenger RNA (mRNA) for angiotensinogen and ANP was measured by a sensitive radiodensitometric cDNA hybridization assay. For the determination of renal renin mRNA, the 760-base pair Rsa I fragment containing the last exon of the rat renin gene was used as a probe for a radiodensitometric assay. In the high sodium state, plasma renin concentration (PRC), renal renin concentration (RRC) and renal renin mRNA decreased by 88% , 90% and 75% respectively. In the low sodium state,PRC,RRC,and renin mRNA increased 17-fold,2.5-fold and 4.5-fold respectively. With captopril treatment during sodium depletion, PRC and renin mRNA increased 144-fold and 17.1-fold respectively, and RRC increased 4.2-fold. The angiotensinogen mRNA level in the liver and kidney decreased in the high sodium state and increased in the low sodium state to similar extents. Captopril treatment decreased angiotensinogen mRNA in both organs by about half. Plasma ANP and ANP mRNA decreased in the low sodium state compared to the high sodium state, while atrial ANP content was unaltered in both low and high sodium states. These results demonstrate that sodium intake affects the expression of the renin, angiotensinogen and ANP genes. In both SHR and Wistar Kyoto rats (SHR) that were 4,8,12 and 16 weeks of age, PRA and PAC in SHR did not differ from these in WKY. Renal renin mRNA level and ANP mRNA level in the atrium did not change in both SHR and WKY. These data suggested that renal renin and atrial ANP may not contribute to increase the blood pressure.