THE ESTIMATION OF HUMAN RENIN-SUBSTRATE CONCENTRATION BY RADIOIMMUNOASSAY OF ANGIOTENSIN I

1973 ◽  
Vol 57 (2) ◽  
pp. 329-330 ◽  
Author(s):  
M. A. WAITE ◽  
M. TREE ◽  
ELIZABETH A. McDERMOTT
Keyword(s):  
Substrate Concentration ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Human Renin

ESTIMATION OF MARSUPIAL RENIN USING MARSUPIAL RENIN-SUBSTRATE

1972 ◽  
Vol 53 (1) ◽  
pp. 125-130 ◽  
Author(s):  
PAMELA A. SIMPSON ◽  
J. R. BLAIR-WEST
Keyword(s):  
Substrate Concentration ◽  
Structural Difference ◽  
Plasma Renin ◽  
Angiotensin I ◽  
Ph Optimum ◽  
Ph Profile ◽  
Renin Substrate ◽  
Grey Kangaroo ◽  
Rate Of Reaction ◽  
Highly Correlated

SUMMARY Bilateral nephrectomy of an Eastern Grey kangaroo (Macropus giganteus) increased plasma renin-substrate concentration approximately tenfold when compared with intact kangaroos. A preparation made from this plasma had a renin-substrate concentration of 3000 ng/ml. A pH profile of rate of reaction with pig renin had an optimum at pH 5·39. By comparison, the pH optimum of sheep renin-substrate was pH 6·15. Estimates of plasma renin concentration for kangaroos, wombats and wallabies, using kangaroo renin-substrate or sheep renin-substrate were highly correlated. Results from incubation with sheep renin-substrate were greater and hence indicate the advantage in using this substrate for marsupial renin estimation. The consistently large difference between sheep and kangaroo renin-substrate when incubated with renin from marsupial and eutherian species appears to be due to a structural difference between the two substrates, probably near the C-terminal end of the angiotensin I molecule.

Lack of inhibition of human renin by human des-angiotensin I renin substrate

1981 ◽  
Vol 30 (18) ◽  
pp. 2630-2631 ◽  
Author(s):  
Kunio Hiwada ◽  
Yukimi Sogo ◽  
Yasuharu Takada ◽  
Tatsuo Kokubu
Keyword(s):  
Angiotensin I ◽  
Renin Substrate ◽  
Human Renin

scholarly journals Properties of renin substrate in rabbit plasma with a note on its assay

1968 ◽  
Vol 108 (4) ◽  
pp. 687-692 ◽  
Author(s):  
J W Ryan ◽  
J. K. McKenzie
Keyword(s):  
Substrate Concentration ◽  
Rabbit Plasma ◽  
Selective Inhibitors ◽  
Angiotensin I ◽  
Renin Substrate ◽  
First Order ◽  
Plasma Enzymes ◽  
First Order Kinetics ◽  
Time Required ◽  
Substrate Concentrations

1. Rabbit plasma enzymes that degrade angiotensin I are inhibited completely by the combination of 2,3-dimercaptopropan-1-ol (10mm), EDTA (10mm) and chlorhexidine gluconate (0·005%, w/v). These compounds do not modify the reaction of renin with renin substrate and are termed the selective inhibitors. 2. The renin substrate concentration of plasma can be measured as angiotensin I content by incubating plasma plus the selective inhibitors with renin for a time sufficient to allow complete utilization of renin substrate. 3. This reaction obeys first-order kinetics to substrate concentrations of at least 1000ng. of angiotensin I content/ml. In general, the renin substrate concentrations of normal rabbit plasmas are less than 1000ng. of angiotensin I content/ml. Thus the time required for the complete release of angiotensin I from normal plasma is inversely related to renin activity and is independent of renin substrate concentration. 4. A method for the assay of renin substrate, taking these reaction kinetics into account, is presented.

MEASUREMENT OF PLASMA RENIN-SUBSTRATE IN MAN

1973 ◽  
Vol 56 (2) ◽  
pp. 159A-171 ◽  
Author(s):  
MALCOLM TREE
Keyword(s):  
Angiotensin Ii ◽  
Substrate Concentration ◽  
Plasma Renin ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Potential Sources ◽  
Sources Of Variation ◽  
Method Of Measurement ◽  
Inhibitor Solution

SUMMARY Values of plasma renin-substrate concentration in man vary widely according to the method of measurement used. Potential sources of variation have been tested and, as far as possible, excluded in the method described here. Blood was diluted rapidly in an angiotensinase-inhibitor solution containing EDTA and phenanthroline; plasma was separated by centrifugation and the renin-substrate in the specimen was hydrolysed by renin to angiotensin I which was identified as such by chromatography and radioimmunoassay. Angiotensin I was used as a standard to determine the amount of angiotensin formed on incubation. Use of angiotensin II for a standard, as in other methods, led to falsely low values of plasma renin-substrate concentration. Recovery of added substrate was 94%. Changes of plasma renin-substrate concentration in some physiological and pathological states are reported briefly.

Effect of Prostaglandins (E2 and A2) on the Enzymatic Reaction of Human Renin in Isolated Homologous System and with Added Normal and Hypertensive Plasma

1974 ◽  
Vol 48 (s2) ◽  
pp. 307s-309s
Author(s):  
P. Eggena ◽  
J. Barrett ◽  
M. Sambhi
Keyword(s):  
Prostaglandin E2 ◽  
Substrate Concentration ◽  
Enzymatic Reaction ◽  
Product Formation ◽  
Inhibitory Effect ◽  
Renin Substrate ◽  
Enzyme Substrate ◽  
Normal Plasma ◽  
Human Renin ◽  
Prostaglandin A2

1. Prostaglandin E2 significantly inhibits the renin reaction in whole plasma as well as in the isolated system of semi-purified human renin and human renin substrate. The inhibitory effect of prostaglandin A2 was less marked in whole plasma and absent in the isolated system. 2. The inhibitory effect of prostaglandin E2 was more marked in normal than hypertensive plasma and was maximal at the lowest concentration used. In hypertensive plasma the maximal inhibitory effect was achieved at tenfold higher concentrations. 3. In normal plasma prostaglandin E2 does not affect the rate of product formation (k5 = k6), but inhibits the overall renin reaction by decreasing the total amount of available enzyme-substrate and enzyme-substrate modifier complex (K2K3). 4. In hypertensive plasma prostaglandin E2 acts as a potential accelerator of the rate of product formation (k6k5). In the range of substrate concentration employed, the apparent inhibitory effect is explained by an even greater lack of available complex (K2K3). This behaviour in hypertensive plasma is consistent with the presence of an additional modifier (? activator).

Immunochemical Differences between Angiotensin I-Forming Enzymes in Man

1980 ◽  
Vol 59 (s6) ◽  
pp. 41s-44s ◽  
Author(s):  
J. Menard ◽  
F.-X. Galen ◽  
C. Devaux ◽  
N. Kopp ◽  
Colette Auzan ◽  
...  
Keyword(s):  
Human Brain ◽  
Amniotic Fluid ◽  
Human Plasma ◽  
Plasma Renin ◽  
Rat Plasma ◽  
Brain Extract ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Human Renin ◽  
Brain Extracts

1. Human plasma, amniotic fluid and acidified amniotic fluid were incubated at pH 5.5 with the same concentrations of human plasma renin substrate and rat plasma renin substrate. They produced three to eight times more angiotensin I with human than with rat renin substrate. By contrast, human brain extracts generated 20 times more angiotensin I when incubated with rat plasma renin substrate than with human plasma renin substrate. 2. Serial dilutions of anti-(human renin) antibody inhibited, in a dose-dependent manner, the production of angiotension I when plasma, amniotic fluid and brain extracts were incubated with human plasma renin substrate. They also inhibited the production of angiotensin I when plasma and amniotic fluid were incubated with rat plasma renin substrate. They were ineffective on the angiotensin I generation by human brain extracts acting on rat plasma renin substrate. 3. Affinity chromatography on an haemoglobin-Sepharose gel separated the fraction of brain extract acting on human renin substrate and inhibited by anti-(human renin) antiserum; this was not retained on the gel at pH 3.3. Part of the angiotensin I-forming activity detected by rat renin substrate hydrolysis was not retained on the gel and part was eluted at pH 8.5. These angiotensin I-forming activities did not hydrolyse human renin substrate, and were not neutralized by anti-(human renin) antibody. 4. These results demonstrate that a renin, immunochemically identical with renal, plasma and amniotic fluid renin, is present in the human brain. Other angiotensin I-forming activity, acting on an heterologous substrate at a more acidic pH, is also present in human brain.

Trypsin activation of inactive renin: plasma blanks and angiotensin I radioimmunoassay

1991 ◽  
Vol 69 (9) ◽  
pp. 1315-1320 ◽  
Author(s):  
Jack D. Barrett ◽  
Peter Eggena
Keyword(s):  
Substrate Concentration ◽  
Rat Plasma ◽  
Direct Proportion ◽  
Trypsin Treatment ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Active Renin ◽  
Normal Plasma ◽  
Inactive Renin ◽  
Significant Bearing

Divergent conclusions exist as to whether inactive renin is present in nephrectomized rat plasma. A major factor contributing to this conflict may be related to significant changes in the "plasma blank" when trypsin-treated plasma is subjected to angiotensin I (AI) radioimmunoassay (RIA). In normal, but not nephrectomized rat plasma, AI-like substances are present in direct proportion to active renin. These substances are destroyed by trypsin. However, trypsin generates additional AI-like material, in both normal and nephrectomized rat plasma. This material, which is present in proportion to the renin substrate concentration, does not appear to be tetradecapeptide (TDP). In normal plasma, however, exogenous TDP is converted to AI in proportion to the active renin concentration and AI generation from TDP is increased by activation of inactive renin. However, in nephrectomized rat plasma, no AI generation from TDP was evident either before or after trypsin treatment. The coincident tryptic generation of a substance that quenches the levels of AI detected by RIA, combined with significant changes in the levels of endogenous and trypsin generated AI-like substances, may have significant bearing on the measured levels of inactive renin.Key words: prorenin, nephrectomy, angiotensin I radioimmunoassay, rat, plasma blanks.

Measurement of inactive renin in normal, nephrectomized, and adrenalectomized rats

1991 ◽  
Vol 69 (9) ◽  
pp. 1381-1384 ◽  
Author(s):  
Knud Poulsen ◽  
Arne Høj Nielsen ◽  
Arne Johannessen
Keyword(s):  
Animal Model ◽  
Exchange Resin ◽  
Cation Exchange Resin ◽  
Plasma Renin ◽  
Rat Plasma ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Suitable Animal Model ◽  
Inactive Renin ◽  
Adrenalectomized Rats

In a new method for measurement of inactive rat plasma renin, the trypsin generated angiotensin I immunoreactive material, which was HPLC characterized as similar to tetradecapeptide renin substrate, is removed by a cation exchange resin before the renin incubation step. The method also corrects for trypsin destruction of endogenous angiotensinogen by the addition of exogenous angiotensinogen. When measured with this method inactive renin in rat plasma decreased after nephrectomy and increased after adrenalectomy. This is in accordance with findings in humans. A sexual dimorphism of prorenin (inactive renin) in rat plasma, similar to that reported in humans and mice, was demonstrated. Thus, inactive renin in the rat is no exception among species, and the rat might be a suitable animal model for further studies dealing with the physiology of prorenin in plasma and tissues.Key words: angiotensinogen, inactive renin, renin.

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