Immunohistochemistry of the renin-angiotensin-system in the kidney.

Changes of the intrarenal localization and concentration of renin in comparison to those of angiotensin II (ANG II) are shown under various conditions of stimulation and inhibition of the renin-angiotensin-system. Evidence is presented that ANG II which is detectable by immunocytochemical methods in epitheloid cells is formed locally within the kidney either intra- or extracellularly. ANG II-like activity was found not only in the epitheloid cells of the JGA, but also further upstream in non specialized, "plain" smooth muscle cells of the renal arterial tree and in the medial muscle cells of resistance vessels in other organs and tissues. This ANG II-like activity of resistance vessels is increased in spontaneously hypertensive rats suggesting a possible role in the long-term regulation of blood pressure.