On Angiotensin-Degrading Aminopeptidases in the Rat Kidney

ISBN-13: 9783540114529 / Angielski / Miękka / 1982 / 88 str.

P. Kugler;T. Telger

Opis

The octapeptide angiotensin II (ANG II, Fig. 1) is the key effector substance of the renin-angiotensin system (RAS) (Werning 1972, Page and Bumpus 1974, Hierholzer 1977, Vecsei et al. 1978, Johnson and Anderson 1980 lit. ). ANG II is formed in two enzymatic steps. Renin acts on renin substrate, a glycoprotein, to produce angiotensin I (ANG I, a decapeptide), which in turn is acted upon by converting enzyme to form ANG II (Skeggs et al. 1968, Fig. 1). Renin substrate (angiotensinogen) is produced mainly in the liver (Page et al. 1941) and is a constituent of the ~-globulin fraction in the circulating plasma (Plentl et al. 1943). The two enzymes involved in the formation of ANG II from renin substra- te are formed at various sites in the body. Renin (E. C. 3. 4. 99. 19) is produced mainly in the granular epithelioid cells of the kidney (Cook 1971, Taugner et al. 1979, Davi- doff and Schiebler 1981), and converting enzyme (CE, E. C. 3. 4. 15. 1) occurs chiefly in the lung (Ng and Vane 1967, Bakhle 1974 lit. ) as well as in numerous other tissues, such as the juxtaglomerular apparatus of the kidney (Granger et al. 1969, 1972) and the brush border of the renal proximal tubule (Ward et al. 1975, 1976; Ward und Erdos 1977). The biological effects of ANG II are numerous.

Spis treści

1 Introduction.- 2 Materials and Methods.- 2.1 Material.- 2.2 Qualitative Histochemistry.- 2.2.1 Light Microscopy.- 2.2.2 Ultracytochemistry of Aminopeptidase A.- 2.3 Quantitative Enzyme Histochemistry of Aminopeptidase A.- 2.3.1 Determination of the Absorption Spectrum of the Azo Dye from 4-Methoxy-2-naphthylamine and Purest-Grade Fast Blue B.- 2.3.2 Enzyme-Kinetic Studies.- 2.3.3 APA Activity Pattern Along the Rat Nephron.- 2.4 Biochemistry of APA and APM.- 2.4.1 Fluorometry of Renal Homogenate from Male Rats.- 2.4.2 Photometry of Renal Homogenate from Male Rats.- 2.4.3 Fluorometric Measurements of Microdissected Glomeruli (Rat).- 2.5 Methods of Investigating Kidneys from Experimental Animals.- 2.6 Chemicals and Suppliers.- 2.7 Abbreviations.- 3 Results.- 3.1 Methodological Studies.- 3.1.1 Qualitative Light-Microscopic Histochemistry.- 3.1.2 Ultracytochemistry.- 3.1.3 Quantitative Histochemistry.- 3.1.4 Biochemistry of APA and APM.- 3.2 Histochemical Localization of APA and APM in the Normal Kidney.- 3.2.1 Juxtaglomerular Apparatus.- 3.2.2 Renal Corpuscle.- 3.2.3 Proximal Tubule.- 3.2.4 Additional Reaction Sites of APA and APM.- 3.3 Animal Experiments.- 3.3.1 Low-Sodium Diet.- 3.3.2 High-Sodium Diet.- 3.3.3 Adrenalectomy.- 4 Discussion.- 4.1 Methodological Aspects.- 4.2 Animal Experiments.- 4.2.1 Juxtaglomerular Apparatus.- 4.2.2 Renal Corpuscle.- 4.2.3 Proximal Tubule.- 4.2.4 Renal Homogenate.- 4.3 Conclusion.- 5 Summary.- References.