POTS NET mRNA Functional Correlation With NET Activity

Active, not recruiting

• Conditions: Postural Tachycardia Syndrome
• Interventions: Diagnostic Test: NET mRNA level; Diagnostic Test: Plasma catechols; Diagnostic Test: Urine Catechols

• Registration Number: NCT03218761
• Lead Sponsor: Vanderbilt University Medical Center

Brief Summary

DNA Acetylation can be responsible for significant down-regulation of transcription of the Norepinephrine Transporter (NET). NET is an important clearance transporter that removes norepinephrine (NE) from sympathetic neuronal synapses. Very low levels of NET can "cause" Postural Tachycardia Syndrome (POTS) or make these patients more susceptible to certain medications. Quantified NET messenger RNA (mRNA) levels from a peripheral blood sample may be able to assess NET availability, which is simpler than older methods. This has not been validated against NET function. In this protocol, the investigators seek to assess whether these NET mRNA levels correlate with NET function. The investigators will assess the DHPG (NET dependent NE metabolite):NE ratio in POTS patients and control subjects from both plasma and urine samples.

Detailed Description

Work from The Baker Institute in Melbourne, Australia has shown that there can be significant epigenetic modification of the Norepinephrine Transporter (NET). DNA Acetylation can be responsible for significant down-regulation of transcription. NET is an important clearance transporter that removes norepinephrine (NE) from sympathetic neuronal synapses.Very low levels of NET can produce a hyperadrenergic phenotype and can "cause" Postural Tachycardia Syndrome (POTS). The Baker Institute researchers have started using quantified NET mRNA levels from a peripheral blood sample to assess NET availability. This is a huge advance due to its simplicity, in contrast to a prior method which involved a vein biopsy to look at the level of protein expression.

In this protocol, the investigators seek to assess whether these NET messenger RNA (mRNA) levels correlate with NET function. When NET transports NE back into presynaptic neurons, a high percentage gets converted to a metabolite (DHPG) and then released into the blood stream. Therefore, the ratio of DHPG:NE ratio is decreased with reduced NET activity. The investigators will assess this DHPG:NE ratio in POTS patients and control subjects from both plasma and urine samples.

Basic Information
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Recruitment & Eligibility
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Study & Design
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Trial Locations

Study Timeline

• Study First Submitted: 2017-07-12
• Study First Submitted QC: 2017-07-12
• Study Start: 2017-07-14
• Study First Posted: 2017-07-17
• Status Verified: 2024-10
• Last Update Submitted: 2024-10-01
• Last Update Posted: 2024-10-02
• Primary Completion: 2027-12-31
• Study Completion: 2027-12-31

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 200

Inclusion Criteria

• • Postural Tachycardia Syndrome

  • Previously diagnosed with POTS

    • Control Subjects

  • Not diagnosed with POTS

    • Age between 13-80 years
    • Male and female subjects are eligible.
    • Able and willing to provide informed consent (if ≥18 years) or assent with parental consent (if age 13-17 years)

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Exclusion Criteria

• • Inability to give, or withdrawal of, informed consent

  • Use of serotonin-norepinephrine reuptake inhibitors (SNRI) or NET inhibitors within 1 month

    o These drugs pharmacologically block NET activity

  • Use of Tricyclic antidepressants within 1 week

    o Many tricyclic antidepressants pharmacologically block NET activity

  • Other factors which in the investigator's opinion would prevent the subject from completing the protocol.

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Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
POTS Patients	Urine Catechols	Patients who self-identify as having Postural Tachycardia Syndrome. They will have assessment of NET mRNA levels, supine plasma catechols, standing plasma catechols, and urine catechols.
Control Subjects	Plasma catechols	Subjects who do not have Postural Tachycardia Syndrome. They will have assessment of NET mRNA levels, supine plasma catechols, standing plasma catechols, and urine catechols.
POTS Patients	Plasma catechols	Patients who self-identify as having Postural Tachycardia Syndrome. They will have assessment of NET mRNA levels, supine plasma catechols, standing plasma catechols, and urine catechols.
Control Subjects	Urine Catechols	Subjects who do not have Postural Tachycardia Syndrome. They will have assessment of NET mRNA levels, supine plasma catechols, standing plasma catechols, and urine catechols.
POTS Patients	NET mRNA level	Patients who self-identify as having Postural Tachycardia Syndrome. They will have assessment of NET mRNA levels, supine plasma catechols, standing plasma catechols, and urine catechols.
Control Subjects	NET mRNA level	Subjects who do not have Postural Tachycardia Syndrome. They will have assessment of NET mRNA levels, supine plasma catechols, standing plasma catechols, and urine catechols.

Primary Outcome Measures

Name	Time	Method
Supine Plasma DHPG:NE correlation	1 day	NET mRNA above and below median supine plasma DHPG:NE

Secondary Outcome Measures

Name	Time	Method
Standing Plasma DHPG:NE correlation	1 day	NET mRNA above and below median standing plasma DHPG:NE
Urine DHPG:NE correlation	1 day	NET mRNA above and below median urine DHPG:NE

Trial Locations

Locations (1)

Vanderbilt University Medical Center; 🇺🇸 Nashville, Tennessee, United States