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

点击翻译按钮获取中文摘要

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.