Variability in Adrenergic Response

October 25, 2018 updated by: C. Michael Stein, Vanderbilt University
The goal of this project is to determine the genetic factors contributing to interindividual differences in response to physiological and pharmacological vasoconstrictors and vasodilators.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The dorsal hand vein model is a relatively non-invasive and robust experimental model to examine the local in vivo effect of vasoactive drugs without elucidating systemic counterregulatory reflexes. Infusion of incremental low doses of phenylephrine into a dorsal hand vein results in increasing local venoconstriction, without systemic effects. Similarly, infusion of incremental low doses of nitroglycerin into a preconstricted dorsal hand vein results in increasing local venodilation, without systemic effects. Systemic vascular responses can be measured by the cold pressor test (CPT),that leads to increase in blood pressure and heart rate , or mental stress that is also known to stimulate cardiovascular responses. Individuals vary in their local and systemic vascular responses but the genetic determinants of these are not clear.

Study Type

Interventional

Enrollment (Actual)

106

Phase

  • Not Applicable

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

  • United States
    • Tennessee
      • Nashville, Tennessee, United States, 37232
        • Vanderbilt University Medical Center

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 40 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Age between 18 and 40 years, inclusive.
  • Subject must be willing to give written informed consent and be able to adhere to diet and study schedules.
  • Subjects must be free of any clinically significant disease that requires a physician's care and/or would interfere with the study evaluations.
  • Subjects must have a normal or clinically acceptable physical examination and ECG.
  • Clinical laboratory tests (CBC, blood chemistries, and urinalysis) must be within normal limits or clinically acceptable to the investigator.

Exclusion Criteria:

  • Any subject who has taken any prescription or over-the-counter drugs, other than oral contraception if female, within two weeks prior to study drug administration.
  • Subjects who are presently, or were formerly, narcotic addicts or alcoholics.
  • Subjects who have a clinically significant allergy/intolerance to phenylephrine.
  • Females with a positive serum/urine pregnancy test at screening.
  • Females who are nursing.
  • Subject using sildenafil or other phosphodiesterase inhibitors.

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: Other
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: African Americans
Subjects' hand veins will be measured for maximum constriction while being infused with phenylephrine, and then mental stress and cold pressor testing
Drug: Phenylephrine
Intravenous phenylephrine at low doses (approximately 10 doses ranging from 0-5000 ng/min) Intravenous nitroglycerin at low doses (approximately 10 doses ranging from 0.05-100 ng/min)
Other Names:
  • generic medications used,not applicable
Experimental: Caucasians
Subjects' hand veins will be measured for maximum constriction while being infused with phenylephrine, and then mental stress and cold pressor testing
Drug: Phenylephrine
Intravenous phenylephrine at low doses (approximately 10 doses ranging from 0-5000 ng/min) Intravenous nitroglycerin at low doses (approximately 10 doses ranging from 0.05-100 ng/min)
Other Names:
  • generic medications used,not applicable

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
ED50 After Phenylephrine
Time Frame: 70 minutes
ED50 is a measurement of vein constriction and indicates 50% of maximal constriction after being given medication phenylephrine, representing sensitivity to the drug. Phenylephrine was infused at increasing dose rates, ranging from 12-9600 ng/min. The infusion at each dose rate lasted 7 minutes, with the vein diameter measured during the last 2 minutes of the infusion. The number represents the ng/ml of phenylephrine needed to reach 50% of maximal vein constriction. ED50 values were not normally distributed and were log-transformed for analysis and expressed as geometric means.
70 minutes

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Blood Pressure
Time Frame: baseline to 2 minutes
change in systolic and diastolic blood pressure, comparing before and after cold pressor test. A subset of 57 participants (of the 106) who were in the primary outcome measure also participated in the cold pressor test.
baseline to 2 minutes

Collaborators and Investigators

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

Sponsor

Vanderbilt University

Collaborators

National Heart, Lung, and Blood Institute (NHLBI)
National Center for Research Resources (NCRR)

Investigators

  • Principal Investigator: Charles M Stein, MD, Vanderbilt University

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.

General Publications

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

January 1, 2009

Primary Completion (Actual)

December 1, 2010

Study Completion (Actual)

December 1, 2011

Study Registration Dates

First Submitted

February 4, 2009

First Submitted That Met QC Criteria

February 5, 2009

First Posted (Estimate)

February 6, 2009

Study Record Updates

Last Update Posted (Actual)

October 26, 2018

Last Update Submitted That Met QC Criteria

October 25, 2018

Last Verified

October 1, 2018

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 71148
  • P01HL056693 (U.S. NIH Grant/Contract)
  • 1UL1RR024975 (U.S. NIH Grant/Contract)

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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