Nitric Oxide and the Autonomic Nervous System

Vanderbilt University

Status: Completed

Conditions: Hypertension; Pure Autonomic Failure

Treatments: Drug: L-NMMA; Drug: Trimethaphan

Study type: Interventional

Funder types: Other

Identifiers

NCT00178919

NIH 1RO1HL71172

010876

Details and patient eligibility

About

The amount of blood flowing to the different parts of the body is regulated by the autonomic (automatic) nerves and by local factors produced by the blood vessels. Nitric oxide (NO) is one of the most important of these metabolic factors. If the production of NO is slowed or stopped the amount of blood to the different parts of the body is decreased. There is increasing knowledge that NO mechanisms are impaired in a number of medical conditions. NO function is reduced in patients with risk factors for atherosclerosis (hardening of the arteries) such as hypercholesterolemia (patients with high cholesterol), or diabetes mellitus, and is also impaired in smokers. This NO "deficiency" is believed to contribute to the greater cardiovascular risk that marks these patient populations. This study is designed to examine if endothelial nitric oxide is an important control mechanism of blood pressure under normal conditions, and if impairment of nitric oxide contributes to hypertension.

Enrollment: 112 patients

Sex: All

Ages: 18 to 85 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Adult subjects.
• 18 to 85 years.
• Non-smokers or long term smokers for specific aim 6.
• Drug-free.
• Long term hypertension in specific substudy 3, patients with autonomic failure in specific aims 4 and 5, diabetes mellitus in specific aim 5.

Exclusion criteria

• Being on any medication other than antihypertensives (for hypertensives), autonomic medications (for autonomic failure [AF] patients), insulin or other treatment for diabetes (for diabetic patients).
• Having pulmonary, renal, hematopoietic, hepatic and/or cardiac disease.

Trial design

112 participants in 2 patient groups

Autonomic Failure Patients

Experimental group

Description:

To compare the effects of NO inhibition during intact and transient pharmacological blockade of the autonomic nervous system in Patients with Autonomic Failure.

Treatment:

Drug: L-NMMA

Drug: Trimethaphan

Controls and hypertensives

Experimental group

Description:

To compare the effects of NO inhibition during intact and transient pharmacological blockade of the autonomic nervous system in normal volunteers and hypertensive subjects.

Treatment:

Drug: L-NMMA

Drug: Trimethaphan