Clinical trial NCT00001628: The Role of Angiotensin Type I Receptor in the Regulation of Human Peripheral Vascular Function
Official title: The Role of Angiotensin Type I Receptor in the Regulation of Human Peripheral Vascular Function
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE3
Conditions: Atherosclerosis
Heart Failure, Congestive
Hypertension
Myocardial Infarction
Keywords: Angiotensin Receptor Antagonist
Atherosclerosis
Blood Flow
Endothelium
Endothelial Dysfunction
Lead sponsor: National Institutes of Health Clinical Center (CC)
Sponsor class: NIH
First posted: 2002-12-10
Enrollment: 36
Sex: ALL
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Primary purpose: TREATMENT

Brief summary: 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: 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.

Eligibility 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.

Primary outcomes:
Secondary outcomes:
Other outcomes:
Locations:
city: Bethesda
country: United States
facility: National Heart, Lung and Blood Institute (NHLBI)
state: Maryland
Study officials:
References:
citation: 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.
citation: 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.
citation: 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.