Activation and measurement of plasma prorenin in the rat

1991 ◽  
Vol 69 (9) ◽  
pp. 1331-1340 ◽  
Author(s):  
P. Ioannou ◽  
A. Y. Loh ◽  
D. H. Osmond
Keyword(s):  
Human Plasma ◽  
Rat Plasma ◽  
Blood Collection ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Blood Samples ◽  
Functional Component ◽  
Fresh Frozen ◽  
Normal Rat

Prorenin determination in rat plasma has been problematic from the outset. Consequently, its existence is questioned by some and its quantity by others, making it difficult for knowledge to advance as to its function relative to the renin system. The present study examines major variables in the determination of rat plasma prorenin and renin, notably different prorenin activation protocols involving blood samples obtained under various conditions from animals under different anesthetics. We found that a trypsin activation step with 5 mg/mL plasma, 60 min at 23 °C, followed by a PRA step of 10 min at 37 °C, resulted in the highest prorenin estimates, up to approximately 400 ng∙mL−1∙h−1 in terms of angiotensin I, as compared with published values of 0–190, based on other protocols. These estimates were obtained despite considerable destruction of angiotensinogen (renin substrate) by trypsin. Cryoactivation of prorenin was much less effective than in human plasma but, when followed by trypsin, it facilitated greater activation than with trypsin alone. Comparable fresh and fresh-frozen plasmas had similar prorenin–renin values, but lower values were observed in plasmas that had been repeatedly frozen and thawed. Conscious rats and those anesthetized with Inactin or ether had higher renins and prorenins than those anesthetized with methoxyflurane or halothane. Rats with kidneys in place during blood collection had higher renins (but not prorenins) than those whose kidneys were clamped off, suggesting that last-minute renin release during blood collection had occurred. We conclude that (i) trypsin generates increased renin, or renin-like, activity in plasma, suggesting activation of a precursor; (ii) on this basis, high prorenin levels exist in normal rat plasma; (iii) renin and prorenin levels are variously influenced by different anesthetics and blood handling procedures; (iv) variation in prorenin levels suggests that it is a dynamic (functional?) component of the renin system; (v) prorenin measurements are heavily influenced by methodological variations during the trypsin step or the subsequent PRA step; (vi) using standardized methodology, the rat can serve as a model for investigating the function of prorenin in normotension and hypertension.Key words: tryptic activation, angiotensinogen, adrenalectomy, anesthesia.

Measurement and characterization of angiotensin peptides in plasma.

1988 ◽  
Vol 34 (6) ◽  
pp. 1046-1051 ◽  
Author(s):  
K Hermann ◽  
D Ganten ◽  
T Unger ◽  
C Bayer ◽  
R E Lang
Keyword(s):  
Angiotensin Ii ◽  
Human Plasma ◽  
Enzyme Inhibitor ◽  
Standard Procedure ◽  
Rat Plasma ◽  
Small Sample ◽  
Blood Collection ◽  
Angiotensin I ◽  
Angiotensin Peptides ◽  
Plasma Angiotensin

Abstract We report a method for the extraction of angiotensin peptides from plasma with a mixture of acetone, 1 mol/L HCl, and water (40/1/5 by vol). The method is highly reproducible for the measurement of angiotensin I and angiotensin II in small sample volumes, with analytical recoveries of about 80% for both peptides. We investigated the influence of sample handling and found a standard procedure for blood collection, plasma preparation, and extraction was essential. The method was used to measure angiotensin I and II in rat and human plasma. In rat plasma, the mean (+/- SEM) concentrations of angiotensin I and angiotensin II were determined to be 67 (+/- 8) and 14 (+/- 1) pmol/L (n = 10), respectively. Neither angiotensin I nor angiotensin II was detectable 24 h after bilateral nephrectomy. Acute oral administration of the converting-enzyme inhibitor ramipril caused a significant increase of angiotensin I from 85 (+/- 6) to 257 (+/- 33) pmol/L (n = 10; P less than 0.001) and a significant decrease of angiotensin II from 12 (+/- 1) to 7 (+/- 0.4) pmol/L in rat plasma (n = 9; P less than 0.001). In human plasma, angiotensin I and angiotensin II values of 21 (+/- 1) and 6.6 (+/- 0.5) pmol/L (n = 10) were found. A single oral dose of the diuretic furosemide increased angiotensin I significantly from 21 (+/- 1) to 32 (+/- 1.7) pmol/L (n = 5); P less than 0.001), whereas angiotensin II remained unchanged, 6.6 (+/- 0.5) vs 6.4 (+/- 0.4) pmol/L (n = 5). Extracted peptides could be identified as [IIe5]-angiotensin I and [IIe5]-angiotensin II by HPLC in combination with specific radioimmunoassays for angiotensin I and angiotensin II.

Biochemical and immunological differences between plasma inactive renin from normal and nephrectomized rats

1991 ◽  
Vol 69 (9) ◽  
pp. 1350-1354 ◽  
Author(s):  
Shokei Kim ◽  
Masayuki Hosoi ◽  
Kiichiro Nakajima ◽  
Kenjiro Yamamoto
Keyword(s):  
Molecular Weight ◽  
Hplc Analysis ◽  
Rat Plasma ◽  
The Other ◽  
Trypsin Treatment ◽  
Angiotensin I ◽  
Active Renin ◽  
Normal Rat ◽  
Inactive Renin

Using immunological techniques, we have demonstrated that about half the trypsin-activatable renin in normal rat plasma is prorenin, while the other is not, and that inactive renin in nephrectomized rat plasma is not prorenin. In the present study, the trypsin-induced angiotensin I generating activity not related to prorenin from normal rat plasma disappeared after HPLC on G3000SW. HPLC analysis of trypsin-treated plasma showed the generation of active renin by trypsin for normal rat plasma, while it did not for nephrectomized rat plasma. These results indicate that trypsin treatment of crude plasma results in the generation of angiotensin I generating activity not due to prorenin, as well as activation of prorenin. HPLC on G3000SW is a useful tool for the determination of plasma prorenin.Key words: prorenin, antibody against prorenin prosegment, trypsin treatment, molecular weight, nephrectomy.

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.

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.

Methods for serial study of renin-angiotensin system in the unanesthetized rat

1975 ◽  
Vol 228 (2) ◽  
pp. 369-375 ◽  
Author(s):  
JS Carvalho ◽  
R Shapiro ◽  
P Hopper ◽  
LB Page
Keyword(s):  
Renin Angiotensin System ◽  
Plasma Renin ◽  
Rat Plasma ◽  
Angiotensin I ◽  
Ether Anesthesia ◽  
Renin Substrate ◽  
Angiotensin System ◽  
Arterial Blood ◽  
Sympathetic Nervous ◽  
Improved Technique

Micromethods for measurement of plasma renin concentration (PRC) and plasma renin-substrate concentration (PSC) have been developed for rat plasma with radioimmunoassay of angiotensin I. An improved technique for aortic implantation of plastic cannulas was developed for use in experiments 1-2 wk in duration. The effects on components of renin system of anesthesia and tail cutting were studied. Arterial blood was sampled through cannulas without animal manipulation. PRC varied little in unanesthetized rats, was moderately and variably increased during pentobarbital anesthesia, and was markedly and consistently elevated during ether anesthesia. PSC was unchanged during anesthesia. PRC was increased in blood obtained by tail cutting within 1-2 min after cutting. With the use of the methods and techniques described here serial studies of the renin system in plasma of unanesthetized rats are shown to be feasible. A role for the sympathetic nervous system in the mediation of renin secretion by ether is proposed.

Base-line and postthermal injury plasma histamine in rats

1986 ◽  
Vol 60 (5) ◽  
pp. 1782-1788 ◽  
Author(s):  
R. W. Yurt ◽  
B. A. Pruitt
Keyword(s):  
Human Plasma ◽  
Thermal Injury ◽  
Sampling Technique ◽  
Rat Plasma ◽  
Base Line ◽  
Plasma Histamine ◽  
Histamine Concentration ◽  
Partial Thickness Burn ◽  
Plasma Histamine Concentration ◽  
Normal Rat

Although plasma histamine concentration has been reported to increase after thermal injury in the rat to as much as 100-fold over normal human plasma levels, the pathophysiological significance and relevance to human disease is questionable. Lack of confidence in the rat as a model of histamine-mediated disease is based on reports that normal rat base-line plasma histamine concentration exceeds that of human plasma by 20- to 70-fold. The present study confirms that high concentrations of histamine (20–68.9 ng/ml) are found in rat plasma obtained in an uncontrolled manner; but concentrations are lower (1.17 +/- 0.49 ng/ml) or undetectable in a sensitive radioenzymatic assay when sampling technique and plasma isolation are controlled. The primary cause for falsely elevated values for plasma histamine concentration appeared to be due to manipulation of the rat. Plasma histamine concentration increased within 1 min after thermal injury and the increase was proportional to extent of surface area injured. In contrast to the finding of a single time-related peak of plasma histamine concentration after partial-thickness burn, a biphasic elevation was found after full-thickness injury. Thus the data indicate that normal rat plasma histamine concentration is similar to that of the human and below the reported threshold for modulation of a variety of immune responses. Furthermore, the data support a role for histamine and other mast-cell mediators in the local and systemic responses to injury.

scholarly journals Renin substrate in granules from rat kidney cortex

1976 ◽  
Vol 154 (3) ◽  
pp. 625-637 ◽  
Author(s):  
B J. Morris ◽  
C I. Johnston
Keyword(s):  
Microsomal Fraction ◽  
Rat Kidney ◽  
Gradient Centrifugation ◽  
Rat Plasma ◽  
Reaction Scheme ◽  
Kidney Cortex ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Rat Kidney Cortex ◽  
Molecular Weights

1. Subcellular fractions of rat kidney cortex generated angiotensin I continuously over 2h when incubated at 37degreesC with rat renin, indicating the presence of renin substrate within cells in the renal cortex. 2. Renin substrate was located in highest specific concentration in particulate fractions. The particles containing renin substrate had a sedimentation velocity slightly lower than mitochondria and renin granules but greater than the microsomal fraction. 3. Isopycnic gradient centrifugation indicated a density of 1.190g/ml for the particles containing renin substrate, compared with 1.201 for renin granules, 1.177 for mitochondria, and 1.170 and 1.230 for lysosomes in the heavy-granule fraction. 4. In the liver, renin substrate was also found in particles, but these had a lower sedimentation rate than those from the kidney. 5. The molecular weights of renin substrate in kidney and liver granules and rat plasma were similar, namely 61000-62000. 6. On the basis of these biochemical findings, a mechanism for the intrarenal production of angiotensin, incorporating a subcellular reaction scheme, is proposed.

Determination of Acotiamide in human plasma by LC-MS/MS and its application to a pharmacokinetic study

2020 ◽  
Vol 17 ◽  
Author(s):  
Qian Sun ◽  
Qiao-gen Zou ◽  
Yun-yan Xia ◽  
Cheng-qun Han
Keyword(s):  
Human Plasma ◽  
Pharmacokinetic Study ◽  
Ammonium Acetate ◽  
Internal Standard ◽  
Rat Plasma ◽  
Pharmacokinetic Studies ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass ◽  
Tandem Mass Spectrometric

Background: A liquid chromatography-tandem mass spectrometric (LC-MS/MS) method had been developed for the quantification of acotiamide in rat plasma and been applied to pharmacokinetic studies. However, there was no LC-MS/MS method been developed for the determination of acotiamide in human plasma and its pharmacokinetic study. Objective: A simple and fast LC-MS/MS method was established and validated for the quantification of acotiamide in human Received: plasma and was applied to a pharmacokinetic study. Methods: Sample preparation was accomplished Revised: Accepted: through protein precipitation, and chromatographic separation was achieved on a Welch, Ultimate XB-C18 column (2.1×50 mm, 3 μm) with a security guard cartridge C18 using a binary gradient with DOI: mobile phase A (Methanol) and B (the solution of 10 mM Ammonium acetate with 0.1% Formic acid) at a flow rate of 400 Results: The retention time of acotiamide and its internal standard, acotiamide-d6 was 1.78 min and 1.79 min, respectively. The total run time was 4.0 min. The method was developed and validated over the concentration range of 0.500-100 ng/mL for acotiamide, with correlation coefficient greater than 0.9987. The extraction recovery was more than 108.43% and the matrix effect was not significant. The inter- and intra-day precisions were below 5.80% and accuracies ranged from 92.7 to 103.0%. Acotiamide was demonstrated to be stable in human plasma under the tested conditions. Conclusion: The validated LC-MS/MS method was successfully applied to study the pharmacokinetic profiles of acotiamide in human plasma after oral administration and has achieved satisfactory results.

Cryoactivation of Plasma Renin

1978 ◽  
Vol 55 (s4) ◽  
pp. 139s-141s ◽  
Author(s):  
A. Hara ◽  
M. Matsunaga ◽  
J. Yamamoto ◽  
K. Morimoto ◽  
H. Nagai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Human Plasma ◽  
Trypsin Inhibitor ◽  
Plasma Renin ◽  
Haemorrhagic Shock ◽  
Rat Plasma ◽  
Renin Activity ◽  
Plasma Samples ◽  
Renin Substrate

1. The mechanism of increased renin activity after human plasma had been kept at −5°C for 4 days (cryoactivation) was investigated. 2. The increase in renin activity of human plasma by cryoactivation was closely correlated to the increase obtained by incubation with trypsin (r = 0·88, P < 0·001, n = 10). 3. An inhibitor of thiol enzyme, N-ethylmaleimide did not inhibit cryoactivation. 4. Soyabean trypsin inhibitor and di-isopropylfluorophosphate (DFP) inhibited cryoactivation, suggesting that the cryoactivation may be due to the action of a trypsin-like serine enzyme. 5. In an experiment in the rat haemorrhagic shock caused parallel increments of renin activity in non-cryoactivated and cryoactivated plasma, the renin activity being about two times higher in the latter. No significant differences were found in the concentrations of renin and renin substrate between the non-cryoactivated and cryoactivated plasma samples. 6. The results may indicate that a destruction of an inhibitor of the renin—renin substrate reaction is responsible for the increase of renin activity after exposure of rat plasma to low temperature. A trypsin-like enzyme in plasma might have destroyed the inhibitor during this procedure.

Intrarenal Formation of Angiotensin II in the Rat: Interference by Saralasin and SQ 20881

1974 ◽  
Vol 48 (s2) ◽  
pp. 37s-40s
Author(s):  
H. Zschiedrich ◽  
K. G. Hofbauer ◽  
E. Hackenthal ◽  
G. D. Baron ◽  
F. Gross
Keyword(s):  
Angiotensin Ii ◽  
Vascular Resistance ◽  
Plasma Renin ◽  
Rat Plasma ◽  
Renal Vascular Resistance ◽  
Angiotensin I ◽  
Renin Substrate ◽  
Vasoconstrictor Effect ◽  
Renal Vascular ◽  
Dose Dependent

1. Isolated rat kidneys were perfused with a medium free of components of the renin-angiotensin system. 2. Angiotensin II, angiotensin I, tetradecapeptide renin substrate or rat plasma renin substrate added to the medium caused a dose-dependent increase of renal vascular resistance. 3. The vasoconstrictor effect of angiotensin II was inhibited by 1-Sar-8-Ala-angiotensin II (Saralasin). The inhibition was dose-dependent, being complete at the highest doses applied. In this dose range, Saralasin increased renal vascular resistance. Saralasin also inhibited vasoconstriction induced by tetradecapeptide renin substrate. 4. The vasoconstrictor effect of angiotensin I was suppressed by SQ 20881, up to a maximum of 87% depending on the dose. Similarly the increase in renal vascular resistance induced by a purified preparation of rat plasma renin substrate was inhibited by 55%; no effect on the action of tetradecapeptide renin substrate was observed. 5. The data suggest that, within the kidney, angiotensin I is converted into angiotensin II to the extent of about 1.25%. Since no angiotensin I is formed from synthetic renin substrate, the vasoconstrictor effect of the tetradecapeptide may be either due to a direct interaction with the angiotensin II receptor or the consequence of the intrarenal formation of angiotensin II. In contrast, the results with rat plasma renin substrate suggest that angiotensin I is formed from ‘natural’ substrate and is subsequently converted into angiotensin II.

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