Conversion of angiotensin I in isolated perfused guinea-pig and rat lung
Increasing concentrations of angiotensin I and different perfusion rates were used to study the conversion of angiotensin I in guinea-pig and rat lungs.
Even the highest concentration used (32.0 μM), which is a thousand times higher than that which occurs in vivo, was unable to saturate the converting system indicating the enormous capacity of this system. SQ 20881 proved to be a reversible inhibitor of the converting system. Its effect on the angiotensin I conversion was greater in guinea-pig lungs than in rat lungs (ID50 was 40.0 nM in guinea-pig lung and above 360.0 nM in rat lungs at a substrate concentration of 38.6 nM).
Key wordsAngiotensin I conversion SQ 20881 Angiotensin II Guinea-pig lung Rat lung
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- Aiken, J. W., Vane, J. R.: The renin-angiotensin system: inhibition of converting enzyme in isolated tissues. Nature (Lond.) 228, 30–34 (1970)Google Scholar
- Aldridge, W. N.: Some properties of specific cholinesterase with particular reference to the mechanism by diethyl-p-nitrophenol thiosulphate (E 605) and analogues. Biochem. J. 46, 451–460 (1950)Google Scholar
- Bakhle, Y. S.: Inhibition of angiotensin I converting enzyme by venom peptides. Brit. J. Pharmacol. 43, 252–254 (1971)Google Scholar
- Dixon, M.: The determination of enzyme inhibitor constants. Biochem. J. 55, 170–171 (1953)Google Scholar
- Giertz, H., Hahn, F., Opferkuch, W., Schmutzler, W.: Vergleichende Untersuchungen über den anaphylaktischen Schock und den Anaphylatoxinschock an der isolierten Meerschweinchenlunge. Naunyn-Schmiedebergs Arch. exp. Path. Pharmak. 242, 42–64 (1961)Google Scholar
- Haber, E., Koerner, T., Page, L. B., Kliman, B., Purnode, A.: Application of a radioimmunoassay for angiotensin I to the physiologic measurements of plasma renin activity in normal human subjects. J. clin. Endocr. 29, 1349–1355 (1969)Google Scholar
- Lineweaver, H., Burk, D.: The determination of enzyme dissociation constants. J. Amer. chem. Soc. 56, 658–666 (1934)Google Scholar
- Ng, K. K. F., Vane, J. R.: Fate of angiotensin I in the circulation. Nature (Lond.) 218, 144–150 (1968)Google Scholar
- Oparil, S., Tregear, V. W., Koerner, T., Barnes, B. A., Haber, E.: Mechanism of pulmonary conversion of angiotensin I to angiotensin II in the dog. Circulat. Res. 29, 682–690 (1971)Google Scholar
- Page, L. B., Haber, E., Kimura, A. Y., Purnode, A.: Studies with the radioimmunoassay for angiotensin II and its application to measurement of renin activity. J. clin. Endocr. 29, 200–206 (1969)Google Scholar