Postural Tachycardia Syndrome
Conditions
Keywords
norepinephrine, norepinephrine transporter
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.
Interventions
DIAGNOSTIC_TESTNET mRNA level
quantification of mRNA to the Norepinephrine Transporter (NET)
DIAGNOSTIC_TESTPlasma catechols
plasma for assay of norepinephrine (NE), DHPG (intraneuronal metabolite of NE), and other catechols
DIAGNOSTIC_TESTUrine Catechols
urine for assay of norepinephrine (NE), DHPG (intraneuronal metabolite of NE), and other catechols
Sponsors
University of Calgary
Dysautonomia International
Vanderbilt University Medical Center
Study design
Observational model
COHORT
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
13 Years to 80 Years
Healthy volunteers
Yes
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)
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Supine Plasma DHPG:NE correlation | 1 day | NET mRNA above and below median supine plasma DHPG:NE |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| 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 |
Countries
United States
Outcome results
None listed