Localization of angiotensinogen and its mRNA in hepatocytes of adult and embryonic rats.

应用原位杂交和免疫细胞化学技术，研究血管紧张素原（ANG）及其mRNA在成年和胚胎大鼠肝细胞中的定位。由于原位杂交技术在肝组织中既有特异性信号，也有非特异性信号，因此本研究主要采用免疫细胞化学方法进行。为此，我们从肾切除大鼠血浆中纯化ANG，制备抗ANG抗体，并通过免疫印迹、放射免疫分析和免疫细胞化学证实其特异性。通过免疫细胞化学，ANG免疫反应性的一个明确的变化，在成年大鼠肝细胞中检测到超过24小时，它是强早期的光周期，而它是弱早期的黑暗时期。反应性的剧烈变化，特别是在门静脉周围肝细胞。24小时内肝细胞中ANG免疫反应性的变化与肝细胞中粗面内质网的数量相似（Uchiyama和Asari 1984）;当肝细胞的蛋白质合成活跃时，肝细胞中ANG含量较高。在生前和生后发育中，妊娠17天肝细胞中出现微弱的ANG，而妊娠20天，ANG的免疫反应变得清晰。出生时，肝细胞中检测到最强的免疫反应性，而出生后5天后肝细胞的反应性与成人肝细胞相似。妊娠17 ~ 20天肝细胞ANG含量增加的结果与肾小球细胞肾素含量增加的结果相似。这表明在胎儿生命末期，ANG作为肾素底物参与了肾素-血管紧张素系统，从而调节血压。

To examine localization of angiotensinogen (ANG) and its mRNA in hepatocytes of adult and embryonic rats, in situ hybridization and immunocytochemistry were applied to liver tissue. In in situ hybridization used, specific as well as non-specific signals appeared in liver tissue, so that the present study was performed mainly using immunocytochemistry. For this, we purified ANG from nephrectomized rat plasma, and prepared anti-ANG, whose specificity was confirmed by immunoblotting, radioimmunoassay and immunocytochemistry. By immunocytochemistry, a clear-cut variation in immunoreactivity for ANG was detected in adult rat hepatocytes over 24 h; it was strong early in the light period, whereas it was weak early in the dark period. The drastic variation in the reactivity was seen especially in periportal hepatocytes. The change in immunoreactivity for ANG in hepatocytes over 24 h is similar to that in quantity of the rough endoplasmic reticulum in hepatocytes (Uchiyama and Asari 1984); ANG content in hepatocytes is high, when proteim synthesis of hepatocytes is active. As for pre- and postnatal development, ANG appeared faintly in hepatocytes at 17 days of gestation, while at 20 days, immunoreactivity for ANG became vivid. At birth, the strongest immunoreactivity was detected in hepatocytes, while the reactivity in hepatocytes after 5 postnatal days became similar to that of adult hepatocytes. The result that ANG content in hepatocytes increases from 17 to 20 days of gestation is similar to that of renin content in juxtaglomerular cells. This indicates that ANG as the renin substrate participates in the renin-angiotensin system at the end of fetal life, which regulates blood pressure.