Red Blood Cell ATP Release and Vascular Function in Humans

February 23, 2020 updated by: Frank Dinenno, Colorado State University
Previous work demonstrates that the red blood cells of older adults do not release a potent vasodilator (ATP) as well as the red blood cells of younger adults. The investigators are targeting a pathway within the red blood cell using fasudil hydrochloride to determine if both the release of ATP from red blood cells and blood flow responses to low oxygen (hypoxia) and exercise in older adults can be improved.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Participants will initiate contact with the investigators by responding to flyers placed in the community either by phone or email. The first correspondence (phone or email) will provide a brief description of the research and ask a series of screening questions to determine age, height, weight, and any medications participants may be taking as well as the current health status (diagnoses, basic health history, and physical activity level) of participants. If they qualify, a two hour screening visit is scheduled during a time when the participant will be examined by the physician. All participants will undergo informed consent in a face to face private meeting with the research coordinator. Following informed consent, participants will be evaluated by a physician and undergo a treadmill stress test to rule out cardiovascular disease.

During the study, heart rate will be monitored with a 3-lead ECG and blood pressure will be monitored noninvasively with a blood pressure cuff on the finger (finometry). Venous blood will be collected at multiple time points via a catheter inserted into a forearm vein draining skeletal muscle circulation for measurement of blood gases (0.5 mL/sample) and plasma [ATP] (2 mL/sample), with less than 100 mL of blood being drawn in total (~60mL total). Blood flow at rest and in response to hypoxia and exercise will be measured non-invasively using Doppler ultrasound of the brachial artery. Hypoxia trials will be performed by having participants breathe a low oxygen gas mixture via a mouthpiece that is hooked up to gas tanks and an anesthesia monitor to decrease their oxygen saturation to ~80% (similar to hiking a 14er) for 10 minutes. Exercise trials will last for approximately 15 minutes and will involve participants performing graded-intensity rhythmic handgrip exercise by lifting weights (corresponding to a low, moderate, and high workload) using a pulley system. The drug treatment used in this study (fasudil) is being given because it may improve red blood cell ATP release in older adults. This is a double-blinded placebo controlled study, thus participation will occur on two randomized experimental days.

Study Type

Interventional

Enrollment (Actual)

31

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • Colorado
      • Fort Collins, Colorado, United States, 80523
        • Colorado State University, Dept. of Health and Exercise Science

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 80 years (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Healthy
  • Sedentary to moderately active
  • 18 to 30 years old for young subjects
  • 60 to 80 years old for older subjects

Exclusion Criteria:

  • Obesity (BMI ≥ 30 kg/m^2)
  • Cardiovascular disease
  • Metabolic disease
  • Use of medications that can influence cardiovascular function
  • Blood pressure greater than or equal to 140/90
  • Smoker
  • Use of hormone replacement therapy

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: BASIC_SCIENCE
  • Allocation: RANDOMIZED
  • Interventional Model: CROSSOVER
  • Masking: TRIPLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: Fasudil hydrochloride
Participants will receive a 100 mL intravenous infusion (in 60 minutes) of 60 mg of fasudil hydrochloride + saline prior to measurements of vascular function and ATP release.
10 mg/mL vial of fasudil hydrochloride. 6 mL (60 mg) of fasudil hydrochloride are added to a 100 mL saline bag for delivery to subjects.
PLACEBO_COMPARATOR: Saline
Participants will receive a 100 mL intravenous infusion (in 60 minutes) of saline (placebo) prior to measurements of vascular function and ATP release.
100 mL saline bag.
Other Names:
  • Placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Forearm Blood Flow Responses to Hypoxia After Administration of Intervention
Time Frame: Within 4 hours after administration of intervention
Forearm blood flow measured using Doppler ultrasound before and after 5 minutes of exposure to hypoxia (breathing a mix of low-oxygen gas and room air to achieve oxygen saturations of ~80%).
Within 4 hours after administration of intervention
Forearm Blood Flow Responses to Exercise After Administration of Intervention
Time Frame: Within 4 hours after administration of intervention
Forearm blood flow measured using Doppler ultrasound before and during continuous rhythmic handgrip exercise at a low, moderate, and high intensity workload (4 minutes at each workload for 12 minutes in total).
Within 4 hours after administration of intervention
Change in ATP Release to Hypoxia After Administration of Intervention
Time Frame: Within 4 hours after administration of intervention
Venous plasma concentrations of ATP measured using a luminometer before and after 5 minutes of exposure to hypoxia (breathing a mix of low-oxygen gas and room air to achieve oxygen saturations of ~80%).
Within 4 hours after administration of intervention
Change in ATP Release to Exercise After Administration of Intervention
Time Frame: Within 4 hours after administration of intervention
Venous plasma concentrations of ATP measured using a luminometer before and during continuous rhythmic handgrip exercise at a low, moderate, and high intensity workload (4 minutes at each workload for 12 minutes in total).
Within 4 hours after administration of intervention

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Arterial Stiffness After Administration of Intervention
Time Frame: Immediately following administration of intervention
Arterial stiffness measured non-invasively using a SphygmoCor system after administration of saline (placebo) and fasudil. This is a randomized crossover design study, so participants will receive 1 treatment (saline or fasudil) on their first visit and the other treatment on their second visit.
Immediately following administration of intervention

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (ACTUAL)

July 14, 2017

Primary Completion (ACTUAL)

October 5, 2018

Study Completion (ACTUAL)

October 5, 2018

Study Registration Dates

First Submitted

November 7, 2017

First Submitted That Met QC Criteria

January 12, 2018

First Posted (ACTUAL)

January 19, 2018

Study Record Updates

Last Update Posted (ACTUAL)

February 27, 2020

Last Update Submitted That Met QC Criteria

February 23, 2020

Last Verified

February 1, 2020

More Information

Terms related to this study

Other Study ID Numbers

  • 16-6361H

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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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