Simultaneous Determination of Plasma Converting Enzyme and Angiotensinase Activity by Radioimmunoassay

1971 ◽  
Vol 40 (6) ◽  
pp. 443-449 ◽  
Author(s):  
K. Poulsen ◽  
L. L. Poulsen
Keyword(s):  
Angiotensin Ii ◽  
Human Plasma ◽  
Rat Plasma ◽  
Least Square ◽  
Converting Enzyme ◽  
Angiotensin I ◽  
Plasma Angiotensin ◽  
Least Square Fit ◽  
Simple Measurement

1. Homologous angiotensin-I was added to untreated plasma. Angiotensin-II which is formed by plasma converting enzyme and subsequently degradated by angiotensinases was determined as a function of time by using radioimmunoassay. Having determined the kinetics, the activities of converting enzyme and angiotensinases were calculated by a least-square fit of the theoretical curve to the experimentally measured values. 2. The method gives a simple measurement of converting-enzyme activity in untreated plasma; in plasma from salt-depleted and renal hypertensive rats this was found to be slightly increased but was normal in plasma from nephrectomized rats. 3. The half-lives for angiotensin-I in normal rat and human plasma were found to vary between 0·8 and 2·1 min, and the possibility that plasma converting enzyme participates in the regulation of the formation of angiotensin-II in vivo cannot be excluded. 4. The angiotensinase activity in rat plasma gave half-lives for angiotensin-II between 1·5 and 3·3 min; the half-life in normal human plasma was 10 min.

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.

Inactivation of Bradykinin and Angiotensin I Conversion in Conscious Rats with Two-Kidney, One-Clip Hypertension

1982 ◽  
Vol 63 (s8) ◽  
pp. 199s-201s ◽  
Author(s):  
Inge E. K. Trindade ◽  
Eduardo M. Krieger
Keyword(s):  
Enzyme Activity ◽  
Angiotensin Ii ◽  
Mean Arterial Pressure ◽  
Renal Artery ◽  
Ang Ii ◽  
Converting Enzyme ◽  
Hypertensive Rats ◽  
Angiotensin I ◽  
Parallel Increase

1. The extents of pulmonary degradation of bradykinin (BK) and angiotensin I (ANG I) to angiotensin II (ANG II) conversion were measured simultaneously to determine whether converting enzyme activity, in vivo, is altered in two-kidney, one-clip hypertensive rats (15, 60 and 180 days after renal artery clipping). 2. Inactivation of BK (estimated by comparing equipressor doses injected intravenously and intra-aortically) was markedly increased in these hypertensive rats: 98.5% (15 days), 98.4% (60 days) and 99.5% (180 days) vs 95.6% in control rats. All groups of hypertensive rats exhibited hyper-reactivity to intra-aortic BK, requiring doses 14–38 times smaller than the control rats to produce the same depressor response. 3. The percentage of ANG I conversion (calculated from equipressor doses of ANG I and ANG II injected intravenously) was elevated after 15 days (46.0% vs 28.1% in control rats), unchanged after 60 days (27.7%) and slightly elevated after 180 days (36.0%). Hyporeactivity to ANG II was observed 15 and 180 days after renal artery clipping (doses six times were needed to produce a standard increase in mean arterial pressure). No alterations were found in the rats at 60 days after artery clipping. 4. The increased degradation of BK cannot be explained solely by elevation of converting enzyme activity since no parallel increase in ANG I conversion was observed, indicating that other bradykininases in the lung may be involved.

The Effect of Captopril on Blood Pressure and Angiotensins I, II and III in Sodium-Depleted Dogs: Problems Associated with the Measurement of Angiotensin II after Inhibition of Converting Enzyme

1980 ◽  
Vol 58 (6) ◽  
pp. 445-450 ◽  
Author(s):  
J. J. Morton ◽  
M. Tree ◽  
J. Casals-Stenzel
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Fold Increase ◽  
Converting Enzyme ◽  
Angiotensin I ◽  
Active Inhibitor ◽  
Arterial Blood ◽  
Rapid Fall ◽  
Angiotensin Iii ◽  
Plasma Angiotensin

1. Changes in arterial blood pressure, blood angiotensin I, plasma angiotensin II and plasma angiotensin III were measured in conscious sodium—depleted dogs after infusion of captopril, an orally active inhibitor of converting enzyme. 2. Angiotensins II and III were measured after chromatography to remove angiotensin I, which increased in concentration after inhibition of converting enzyme and which interfered in the direct assay for angiotensin II. 3. Infusion of captopril at 20, 200, 2000 and 6000 μg h−1 kg−1, each for 3 h, produced a rapid fall in blood pressure and in concentration of angiotensin II. Angiotensin II was undetectable at 6000 μg h−1 kg−1 (mean pre-infusion value for all samples was 39 ± sd 15 pmol/I, n = 14) 4. The percentage fall in blood pressure correlated with the percentage fall in plasma angiotensin II (r = 0.65, P<0.001) 5. These results suggest that the initial fall in blood pressure may be mediated in part by the suppression of angiotensin II. 6. Blood angiotensin I concentration rose with each rate of infusion of drug to a maximum 16-fold increase at 6000 μg h−1 kg−1 (26−416 pmol/l). The rise in angiotensin I was inversely related to the fall in angiotensin II (r = −0.68, P<0.001)

scholarly journals Involvement of human plasma angiotensin I-converting enzyme in the degradation of the haemoregulatory peptide N-acetyl-seryl-aspartyl-lysyl-proline

1993 ◽  
Vol 296 (2) ◽  
pp. 373-378 ◽  
Author(s):  
K J Rieger ◽  
N Saez-Servent ◽  
M P Papet ◽  
J Wdzieczak-Bakala ◽  
J L Morgat ◽  
...  
Keyword(s):  
Human Plasma ◽  
Proteinase Inhibitors ◽  
Negative Regulator ◽  
Haematopoietic Stem Cell ◽  
Converting Enzyme ◽  
Angiotensin I ◽  
Rabbit Lung ◽  
Angiotensin I Converting Enzyme ◽  
Plasma Angiotensin ◽  
Metalloprotease Inhibitors

The degradation of N-Ac-Ser-Asp-Lys-Pro (AcSDKP), a negative regulator controlling the proliferation of the haematopoietic stem cell, by enzymes present in human plasma, has been investigated. Radiolabelled AcSD[4-3H]KP ([3H]AcSDKP, 1 mM) was completely metabolized in human plasma with a half-life of 80 min, leading exclusively to the formation of radiolabelled lysine. The cleavage of AcSDKP was insensitive to classical proteinase inhibitors including leupeptin, but sensitive to metalloprotease inhibitors. The degradation was completely blocked by specific inhibitors of angiotensin I-converting enzyme (ACE; kininase II; peptidyldipeptide hydrolase, EC 3.4.15.1), showing that the first step of the hydrolysis was indeed due to ACE. In dialysed plasma, the hydrolysis proceeded at only 17% of the maximal rate, whereas addition of 20 mM NaCl led to the recovery of the initial rate observed with normal plasma. Hydrolysis of AcSDKP by commercial rabbit lung ACE generated the C-terminal dipeptide Lys-Pro. Thus, ACE cleaves AcSDKP by a dipeptidyl carboxypeptidase activity. In fact the formation of Lys-Pro was observed when AcSDKP was incubated in human plasma in the presence of HgCl2. These results suggest that ACE is involved in the first limiting step of AcSDKP degradation in human plasma. The second step seems to be under the control of a leupeptin- and E-64-insensitive, HgCl2-sensitive plasmatic enzyme.

Functional role of local angiotensin-converting enzyme (ACE) in adrenal catecholamine secretion in vivo

1999 ◽  
Vol 77 (11) ◽  
pp. 878-885 ◽  
Author(s):  
Nobuharu Yamaguchi ◽  
Daniel Martineau ◽  
Stéphane Lamouche ◽  
Richard Briand
Keyword(s):  
Angiotensin Ii ◽  
Adrenal Gland ◽  
Angiotensin Converting Enzyme ◽  
Venous Blood Flow ◽  
Dependent Manner ◽  
Converting Enzyme ◽  
Left Adrenal Gland ◽  
Angiotensin I ◽  
Aortic Blood

The aim of the present study was to investigate whether exogenous angiotensin I (AngI) is locally converted to angiotensin II (AngII), which in turn results in an increase in the adrenal catecholamine (CA) secretion in the adrenal gland in anesthetized dogs. Plasma CA concentrations in adrenal venous and aortic blood were determined by an HPLC-electrochemical method. Adrenal venous blood flow was measured by gravimetry. Local administration of AngI (0.0062 to 6.2 µg, 0.0096 to 9.6 µM) to the left adrenal gland resulted in significant increases in CA output in a dose-dependent manner. Following administration of 0.62 µg (0.96 µM) of AngI, adrenal epinephrine and norepinephrine outputs increased from 20.8 ± 13.6 to 250.9 ± 96.4 ng·min-1·g-1 (p < 0.05, n = 5) and from 2.8 ± 1.7 to 29.6 ± 11.1 ng·min-1·g-1 (p < 0.05, n = 5), respectively. From the same left adrenal gland, the output of AngII increased from -0.02 ± 0.04 to 26.39 ± 11.38 ng·min-1·g-1 (p < 0.05, n = 5), while plasma concentrations of AngII in aortic blood remained unchanged. In dogs receiving captopril (12.5 µg, 0.5 mM) 10 min prior to AngI, the net amounts of CA and AngII secreted during the first 3 min after AngI were diminished by about 80% (p < 0.05, n = 5) compared with those obtained from the control group. There was a close correlation (r2 = 0.91, n = 6) between the net increases in AngII and CA outputs induced by AngI. The results indicate that the local angiotensin converting enzyme is functionally involved in regional AngII formation in the canine adrenal gland in vivo. The study suggests that AngII thus generated may play a role in the local regulation of adrenal CA secretion.Key words: angiotensin I, angiotensin II, captopril, adrenal gland, anesthetized dog.

Direct effects in vivo of angiotensins I and II on the canine sinus node

1991 ◽  
Vol 69 (3) ◽  
pp. 389-392 ◽  
Author(s):  
C. Lambert ◽  
D. Godin ◽  
P. Fortier ◽  
R. Nadeau
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Angiotensin Ii ◽  
Sinus Node ◽  
Converting Enzyme ◽  
Chronotropic Effect ◽  
Angiotensin I ◽  
Sinus Node Artery ◽  
Blood Pressures

The chronotropic responses to angiotensins I and II (5 μg in 1 mL Tyrode's solution) injected into the sinus node artery were assessed before and after the intravenous administration of captopril (2 mg/kg) and saralasin (20 μg/kg) in anaesthetized dogs. The effects of angiotensin II given intravenously were also observed. The animals (n = 8) were vagotomized and pretreated with propranolol (1 mg/kg, i.v.) to prevent baroreceptor-mediated responses to increases in blood pressure. Injection of angiotensin I into the sinus node artery induced significant increases in heart rate (114 ± 6 vs. 133 ± 6 beats/min) and in systemic systolic (134 ± 13 vs. 157 ± 14 mmHg; 1 mmHg = 133.3 Pa) and diastolic (95 ± 10 vs. 126 ± 13 mmHg) blood pressures. Similar results were obtained when angiotensin II was injected into the sinus node artery, but intravenous injection induced changes in systolic (138 ± 8 vs. 180 ± 25 mmHg) and diastolic (103 ± 8 vs. 145 ± 20 mmHg) blood pressures only. Captopril induced a significant decrease in systolic (118 ± 11 vs. 88 ± 12 mmHg) and diastolic (84 ± 9 vs. 59 ± 9 mmHg) blood pressures without affecting the heart rate (109 ± 6 vs. 106 ± 6 beats/min). Saralasin produced a significant increase in systolic (109 ± 7 vs. 126 ± 12 mmHg) blood pressure only. Increments in heart rate and systolic and diastolic blood pressures in response to angiotensins I and II were, respectively, abolished by captopril and saralasin. It was concluded that angiotensin II has, in vivo, a direct positive chronotropic effect that can be blocked by saralasin. The antagonism by captopril of the response to angiotensin I suggests the presence of local tissue converting enzyme activity in the region of the sinus node.Key words: angiotensin, chronotropic effect, tissue converting enzyme.

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