In vivo antihypertensive mechanism of lactoferrin-derived peptides: Reversion of angiotensin I- and angiotensin II-induced hypertension in Wistar rats

Hypertension, or an elevated blood pressure, is the primary modifiable risk factor for cardiovascular disease, the number one cause of mortality worldwide. We previously demonstrated that Th17 activation and interleukin 17A (IL-17A)/IL-21 production is integral for the full development of a hypertensive phenotype as well as the renal and vascular damage associated with hypertension. Rho-associated coiled-coil containing protein Kinase 2 (ROCK2) serves as a molecular switch upregulating Th17 and inhibiting regulatory T cell (Treg) differentiation. We hypothesize that hypertension is characterized by excessive T cell ROCK2 activation leading to increased Th17/Treg ratios and ultimately end-organ damage. We first showed in vitro that KD025, an experimental orally bioavailable ROCK2 inhibitor inhibits Th17 cell proliferation and IL-17A/IL-21 production. To determine if hypertensive stimuli such as endothelial stretch increases T cell ROCK2 expression, we cultured human aortic endothelial cells exposed to 5% (normotensive) or 10% (hypertensive) stretch with circulating human T cells and HLA-DR+ antigen presenting cells. Hypertensive stretch increased T cell ROCK2 expression 2-fold. We then tested the effect of ROCK2 inhibition with KD025 (50mg/kg i.p. daily) in vivo on angiotensin II (Ang II)-induced hypertension. Treatment with KD025 significantly attenuated the hypertensive response within 1 week of Ang II treatment (systolic blood pressure: 139± 8 vs 108±7mmHg) and this persisted for the duration of the 4 week study reaching blood pressures 20 mmHg lower (135±13mmHg) than vehicle treated mice (158±4mmHg p<0.05 effect of treatment 2-way Repeated Measures ANOVA). Flow cytometric analysis of tissue infiltrating leukocytes revealed that KD025 treatment increased Treg/Th17 ratios in the kidney (0.61±0.03 vs 0.79±0.08, p<0.05 student’s t-test). Thus, T cell ROCK2 may be a novel therapeutic target for the treatment of hypertension.

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

Clinical Science ◽

10.1042/cs063199s ◽

1982 ◽

Vol 63 (s8) ◽

pp. 199s-201s ◽

Cited By ~ 1

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.

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Role of nitric oxide resistance in erythropoietin-induced hypertension in rats with chronic renal failure

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1996.271.1.e113 ◽

1996 ◽

Vol 271 (1) ◽

pp. E113-E122 ◽

Cited By ~ 11

Author(s):

N. D. Vaziri ◽

X. J. Zhou ◽

F. Naqvi ◽

J. Smith ◽

F. Oveisi ◽

...

Keyword(s):

Nitric Oxide ◽

Renal Failure ◽

Chronic Renal Failure ◽

Angiotensin Ii ◽

Pressor Response ◽

Magnesium Concentration ◽

Induced Hypertension ◽

Group A

We studied the mechanism of erythropoietin (EPO)-induced hypertension (HTN) in rats with chronic renal failure (CRF). After partial nephrectomy, rats were randomized into four groups. Group A received EPO, 150 U/kg, two times weekly for 6 wk to prevent anemia; group B received placebo injections and became anemic; group C received EPO but was kept anemic by dietary iron deficiency; and group D received placebo and regular transfusions to match hematocrit (Hct) in group A. Blood pressure (BP), Hct, platelet cytosolic calcium ([Ca2+]i) and magnesium concentration, and pressor and vasodilatory responses were determined. By design, Hct in groups A and D were comparable and significantly greater (P < 0.01) than in groups B and C. Despite divergent Hct values, the EPO-treated groups A and C showed a significant rise in BP compared with the placebo-treated groups B and D. HTN occurred whether EPO therapy was begun immediately or 4 wk after nephrectomy. EPO therapy augmented the elevation of basal [Ca2+]i and restored the defective thrombin-mediated rise of platelet [Ca2+]i in CRF animals. EPO therapy did not alter caudal artery contraction in response to either 68 mM K(+)-induced depolarization, angiotensin II or alpha 1-agonist, methoxamine in vitro, or the pressor response to angiotensin II in vivo. However, EPO therapy impaired the hypotensive response to nitric oxide (NO) donors, sodium nitroprusside and S-nitroso-N-acetyl-D,L-penicillamine, and reversed the CRF-induced upregulation of guanosine 3',5'-cyclic monophosphate production by thoracic aorta in vitro. Thus EPO-induced HTN in CRF rats is Hct independent and is associated with and perhaps causally related to increased basal and stimulated [Ca2+]i and impaired vasodilatory response to NO.

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

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y99-094 ◽

1999 ◽

Vol 77 (11) ◽

pp. 878-885 ◽

Cited By ~ 2

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.

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Pressor Response to Angiotensin I and Angiotensin II: The Site of Conversion of Angiotensin I

Clinical Science ◽

10.1042/cs0430839 ◽

1972 ◽

Vol 43 (6) ◽

pp. 839-849 ◽

Cited By ~ 7

Author(s):

E. C. Osborn ◽

G. Tildesley ◽

P. T. Pickens

Keyword(s):

Blood Pressure ◽

Angiotensin Ii ◽

Pressor Response ◽

Left Ventricular ◽

Angiotensin I ◽

Intravenous Injections ◽

Pressor Responses ◽

The Difference

1. The pressor responses to angiotensin I were compared with those to angiotensin II after injections into the left ventricle and jugular vein in the sheep, dog and pig. 2. The ability of angiotensin I to raise the blood pressure was less than that of angiotensin II with both routes of injection, a difference which was more marked after ventricular injection. 3. When equipressor doses of the hormones were given there was a delay of 1–3 s in the onset of the pressor response to angiotensin I compared with angiotensin II after left-ventricular injections; the difference in the delay in onset was less apparent with intravenous injections. 4. The development of the pressor responses was similar with both hormones when equipressor doses were used but the rises in blood pressure were more prolonged with angiotensin I, especially when given by the left-ventricular route. 5. The in vitro rate of activation of angiotensin I by blood was much slower than the apparent in vivo formation of angiotensin II.

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

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y91-059 ◽

1991 ◽

Vol 69 (3) ◽

pp. 389-392 ◽

Cited By ~ 11

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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In-Vivo and In-Vitro Conversion of Angiotensin I to Angiotensin II in Dog Blood

Circulation Research ◽

10.1161/01.res.26.5.591 ◽

1970 ◽

Vol 26 (5) ◽

pp. 591-599 ◽

Cited By ~ 70

Author(s):

SUZANNE OPARIL ◽

CHARLES A. SANDERS ◽

EDGAR HABER

Keyword(s):

Angiotensin Ii ◽

Angiotensin I ◽

Dog Blood

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Simultaneous Determination of Plasma Converting Enzyme and Angiotensinase Activity by Radioimmunoassay

Clinical Science ◽

10.1042/cs0400443 ◽

1971 ◽

Vol 40 (6) ◽

pp. 443-449 ◽

Cited By ~ 15

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.

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