The Role of Angiotensin Type I Receptor in the Regulation of Human Peripheral Vascular Function

NCT ID: NCT00001628

Last Updated: 2008-03-04

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE3

Total Enrollment

36 participants

Study Classification

INTERVENTIONAL

Study Start Date

1997-07-31

Study Completion Date

2000-09-30

Brief Summary

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The renin angiotensin system (RAS) plays an important physiological and pathophysiological role in the control of blood pressure and plasma volume. Inhibition of the RAS is useful in the treatment of hypertension, cardiac failure and in some patients with myocardial infarction. Several recent clinical trials with angiotensin converting enzyme inhibitors (ACEI) have shown that they also reduce the incidence of myocardial infarction, but the mechanisms underlying this anti-ischemic effect are poorly understood. ACEI reduce angiotensin II synthesis and prevent bradykinin degradation. Results from ongoing studies in the Cardiology Branch (Protocol 95-H-0099) designed to investigate the link between ACEI and the vascular endothelium indicate that ACEI improve peripheral endothelial function, an effect that is partially mediated by bradykinin. The current protocol is designed to investigate whether the beneficial effects of ACEI on peripheral endothelial function are also due to inhibition of angiotensin II. The recent development of selective angiotensin II type 1 (AT1) receptor antagonists allows us to specifically examine the effects of angiotensin II on vasomotor activity.

Detailed Description

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The renin angiotensin system (RAS) plays an important physiological and pathophysiological role in the control of blood pressure and plasma volume. Inhibition of the RAS is useful in the treatment of hypertension, cardiac failure and in some patients with myocardial infarction. Several recent clinical trials with angiotensin converting enzyme inhibitors (ACEI) have shown that they also reduce the incidence of myocardial infarction, but the mechanisms underlying this anti-ischemic effect are poorly understood. ACEI reduce angiotensin II synthesis and prevent bradykinin degradation. Results from ongoing studies in the Cardiology Branch (Protocol 95-H-0099) designed to investigate the link between ACEI and the vascular endothelium indicate that ACEI improve peripheral endothelial function, an effect that is partially mediated by bradykinin. The current protocol is designed to investigate whether the beneficial effects of ACEI on peripheral endothelial function are also due to inhibition of angiotensin II. The recent development of selective angiotensin II type 1 (AT1) receptor antagonists allows us to specifically examine the effects of angiotensin II on vasomotor activity.

Conditions

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Atherosclerosis Heart Failure, Congestive Hypertension Myocardial Infarction

Study Design

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Primary Study Purpose

TREATMENT

Interventions

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Angiotensin II type 1 receptor antagonists

Intervention Type DRUG

Eligibility Criteria

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Inclusion Criteria

Patients over 18 years with endothelial dysfunction requiring diagnostic cardiac catheterization.

Normal volunteers or patients undergoing catheterization who have normal coronary arteries without risk factors for atherosclerosis will be used as controls.

No unstable angina.

No significant left main disease (greater than 50% stenosis).

No recent myocardial infarction (less than 1 month).

No pregnancy, lactation.

No allergy to losartan.

No renal failure (creatinine greater than 2.5 mg/dl).

Ability to withdraw ACE inhibitors.
Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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National Heart, Lung, and Blood Institute (NHLBI)

NIH

Sponsor Role lead

Locations

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National Heart, Lung and Blood Institute (NHLBI)

Bethesda, Maryland, United States

Site Status

Countries

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United States

References

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Ontyd J, Schrader J. Measurement of adenosine, inosine, and hypoxanthine in human plasma. J Chromatogr. 1984 May 11;307(2):404-9. doi: 10.1016/s0378-4347(00)84113-4. No abstract available.

Reference Type BACKGROUND
PMID: 6736187 (View on PubMed)

Cockcroft JR, Sciberras DG, Goldberg MR, Ritter JM. Comparison of angiotensin-converting enzyme inhibition with angiotensin II receptor antagonism in the human forearm. J Cardiovasc Pharmacol. 1993 Oct;22(4):579-84. doi: 10.1097/00005344-199310000-00011.

Reference Type BACKGROUND
PMID: 7505360 (View on PubMed)

Gottlieb SS, Dickstein K, Fleck E, Kostis J, Levine TB, LeJemtel T, DeKock M. Hemodynamic and neurohormonal effects of the angiotensin II antagonist losartan in patients with congestive heart failure. Circulation. 1993 Oct;88(4 Pt 1):1602-9. doi: 10.1161/01.cir.88.4.1602.

Reference Type BACKGROUND
PMID: 8403307 (View on PubMed)

Other Identifiers

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97-H-0140

Identifier Type: -

Identifier Source: secondary_id

970140

Identifier Type: -

Identifier Source: org_study_id

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