Sympathetic Regulation of Large Artery Stiffness in Humans With ISH (SELECT)

Sympathetic Regulation of Large Artery Stiffness in Humans With Age-Related Isolated Systolic Hypertension

Stiffening of your blood vessels, particularly the large vessels from your heart (called the aorta and carotids) you age contributes to the development of cardiovascular disease (CVD) such as heart attack and stroke. Nerve activity from your brain to your body also increases with advancing age but it is unknown if this nerve activity contributes directly to the stiffening on your blood vessels in older adults in addition to high blood pressure. Therefore, successful completion of the proposed aims will have a significant clinical impact by identifying if nerve activity from your brain could be a novel target for therapies that would lower stiffness of the aorta and carotid arteries in older adults.

Study Overview

• Status: Completed
• Conditions: Hypertension, Systolic; Stiffness, Aortic
• Intervention / Treatment: Drug: Placebo; Drug: Clonidine; Drug: Hydrochlorothiazide

• Study Type: Interventional
• Enrollment (Actual): 100
• Phase: Early Phase 1

Contacts and Locations

Study Locations

• United States
  • Iowa
    • Iowa City, Iowa, United States, 52242
      • University of Iowa
    • Iowa City, Iowa, United States, 52240
      • Amy Stroud

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 60 years to 85 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• age 60-85
• non-smoking
• clinically healthy
• untreated or treated stage 1 isolated systolic hypertension (ISH) (systolic BP 130-139 mmHg; diastolic BP <90 mmHg) or stage 2 ISH (systolic BP 140-159 mmHg; diastolic BP <90 mmHg) per 2017 AHA/ACC hypertension guidelines
• if subject is on antihypertensive medications, they will stop taking medication for a one-week washout period after Visit 1 before they return for Visit 2. They will come in at day 3 and day 7 of the one-week washout for a BP reading, to confirm that systolic BP is <160 mmHg.

Exclusion Criteria:

• no history of cardiovascular disease (e.g., myocardial infarction, bypass surgery, angioplasty/stent, heart failure, cardiomyopathy, pacemaker/defibrillator, peripheral artery disease), pulmonary disease, liver disease, Type I or II diabetes, cancer (treated by chemotherapy and/or radiation), psychiatric illness, on aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs).
• aspirin, NSAIDs, vitamins, herbal supplements, omega-3-fatty acids will have to discontinue for at least 1 week before participation and remain discontinued during the study.
• blood thinners, serotonin reuptake inhibitors (SSRIs), or PDE5 inhibitors will also be excluded.
• Women must be postmenopausal for at least 6 months (surgical or natural) and not currently on hormone replacement therapy.
• Subjects not on antihypertensive will not be eligible if their resting clinic systolic BP is <130 mmHg or >160 mmHg and diastolic BP >90 mmHg.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo	Drug: Placebo; Placebo
Experimental: Clonidine; 0.2 mg/day oral	Drug: Clonidine; Clonidine 0.2 mg/day oral tablet
Active Comparator: Hydrochlorothiazide; 37.5 mg/day oral	Drug: Hydrochlorothiazide; Hydrochlorothiazide 37.5 mg/day oral tablet

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in carotid-femoral pulse wave velocity	Aortic stiffness	Baseline and after 4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in carotid distensibility index	Change in carotid distensibility	Baseline and after 4 weeks
Change in carotid flow pulsatility index	Change in carotid flow pulsatility	Baseline and after 4 weeks
Change in carotid intimal medial thickness (IMT)	Change in carotid wall thickness	Baseline and after 4 weeks

Collaborators and Investigators

• Sponsor: University of Iowa
• Investigators: Principal Investigator: Gary Pierce, PhD, University of Iowa

Study record dates

Study Major Dates

• Study Start (Actual): June 1, 2021
• Primary Completion (Actual): July 31, 2025
• Study Completion (Actual): July 31, 2025

Study Registration Dates

• First Submitted: June 5, 2020
• First Submitted That Met QC Criteria: June 8, 2020
• First Posted (Actual): June 9, 2020

Study Record Updates

• Last Update Posted (Actual): August 8, 2025
• Last Update Submitted That Met QC Criteria: August 5, 2025
• Last Verified: August 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Essential Hypertension; Vascular Diseases; Cardiovascular Diseases; Heart Murmurs; Isolated Systolic Hypertension; Hypertension; Systolic Murmurs; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Autonomic Agents; Peripheral Nervous System Agents; Sensory System Agents; Analgesics; Neurotransmitter Agents; Membrane Transport Modulators; Adrenergic alpha-2 Receptor Agonists; Adrenergic alpha-Agonists; Adrenergic Agonists; Adrenergic Agents; Diuretics; Natriuretic Agents; Antihypertensive Agents; Sympatholytics; Sodium Chloride Symporter Inhibitors; Clonidine; Hydrochlorothiazide
• Other Study ID Numbers: 202004244

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No