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.

scholarly journals A rapid simple method for the assay of renin in rabbit plasma

1968 ◽  
Vol 108 (4) ◽  
pp. 679-685 ◽  
Author(s):  
J W Ryan ◽  
J. K. McKenzie ◽  
M. R. Lee
Keyword(s):  
Rabbit Plasma ◽  
Selective Inhibitors ◽  
Angiotensin I ◽  
Simple Method ◽  
Renin Substrate ◽  
First Order ◽  
Complete Inactivation ◽  
Plasma Enzymes ◽  
First Order Kinetics ◽  
Percentage Release

1. EDTA (10mm), 2,3-dimercaptopropan-1-ol (10mm) and chlorhexidine gluconate (0·005%, w/v) cause complete inactivation of plasma enzymes that degrade angiotensin I, but have no effect on the reaction of renin with its substrate. The reagents were termed the selective inhibitors. 2. Thus it is possible to measure renin in plasma by its ability to catalyse the release of angiotensin I. 3. Sterile plasma, treated with the selective inhibitors, is incubated with renin substrate (500–1000ng. of angiotensin content/ml.) at pH6 at 42° for 6hr. 4. Under these conditions the reaction obeys first-order kinetics. Renin activity is calculated in terms of the percentage release of the angiotensin content/hr. 5. As described, the assay is sufficiently sensitive to measure renin in the plasma of all normal rabbits. By extending the length of the incubation, much lower activities can be measured.

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.

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.

Enzymatic Activity of Renin in Plasma of Normal and Uraemic Subjects

1984 ◽  
Vol 67 (3) ◽  
pp. 365-368 ◽  
Author(s):  
Theodore A. Kotchen ◽  
Tam T. Guyenne ◽  
Pierre Corvol ◽  
Joel Menard
Keyword(s):  
Renal Failure ◽  
Enzymatic Activity ◽  
Plasma Renin ◽  
Normal Subjects ◽  
Renin Activity ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Inactive Renin ◽  
Substrate Concentrations

1. Plasma renin reactivity (PRR) is the rate of angiotensin I production after addition of renin to plasma, minus endogenous renin activity. PRR is increased in plasma of patients with renal failure compared with that of normal subjects. The present study was carried out to determine if increased PRR in uraemic plasma is related to differences of endogenous active or inactive renin, endogenous renin substrate, or pH of the incubation in vitro. 2. PRR in plasma of ten uraemic patients was greater (P<0.02) than that in plasma of ten normal subjects in incubations carried out at pH 7.4 and 5.7. 3. Increased PRR was not accounted for by differences of endogenous active and inactive renin activity. 4. After addition of renin, renin concentration (measured by direct radioimmunoassay) did not differ in normal and uraemic plasma. 5. Renin substrate concentration, measured both indirectly and by direct radioimmunoassay, also did not differ in normal and uraemic plasma. 6. Increased PRR in uraemic plasma is not related to alterations of renin or renin substrate concentrations. These observations are consistent with our earlier hypothesis that there is a deficiency of a renin inhibitor in uraemic plasma.

scholarly journals A KINETIC ANALYSIS OF THE RENIN-ANGIOTONIN PRESSOR SYSTEM AND THE STANDARDIZATION OF THE ENZYMES RENIN AND ANGIOTONASE

1943 ◽  
Vol 78 (5) ◽  
pp. 367-386 ◽  
Author(s):  
Albert A. Plentl ◽  
Irvine H. Page
Keyword(s):  
Pressor Response ◽  
Accurate Method ◽  
Enzyme Concentration ◽  
Renin Substrate ◽  
First Order ◽  
First Order Kinetics ◽  
Consecutive Reactions ◽  
Slow Decline ◽  
Reaction Constant

The physicochemical background of the renal vasporessor system (renin-renin-substrate, angiotinin, angiotonase) is given. The formation and destruction of angiotonin is shown to consist of two consecutive reactions, both of which follow the laws of first order kinetics. Each reaction was studied separately and its reaction constant found to be proportional to the enzyme concentration. Hence these constants should be used to express the activity of the enzymes, renin and angiotonase. The over-all reaction of a mixture of renin and angiotonase such as occurs in kidney extracts with the α-globulin fraction of serum, viz., rapid increase followed by a slow decline in angiotonin concentration, was found experimentally to correspond closely to the theoretical values calculated for such a reaction. The curve obtained also satisfyingly explains the characteristic pressor response to the intravenous injection of renin. An accurate method for the determination of renin in the presence of angiotonase is presented.

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

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.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH &lt; 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

Sign in / Sign up

Export Citation Format

Share Document