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Trial registered on ANZCTR


Registration number
ACTRN12619001156178
Ethics application status
Approved
Date submitted
1/08/2019
Date registered
19/08/2019
Date last updated
19/02/2021
Date data sharing statement initially provided
19/08/2019
Type of registration
Prospectively registered

Titles & IDs
Public title
Neurovascular coupling in healthy humans
Scientific title
Neurovascular coupling in healthy humans: the role of the sympathetic nervous system
Secondary ID [1] 298901 0
None
Universal Trial Number (UTN)
U1111-1233-5752
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Hypertension 313877 0
Cerebrovascular disease 313878 0
Condition category
Condition code
Neurological 312290 312290 0 0
Studies of the normal brain and nervous system
Cardiovascular 312407 312407 0 0
Hypertension

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
This is a non-therepeutic mechanistic physiological study.

Participants will undertake on initial familarisation visit and one experimental visit. At the familarisation visit participants will complete a general health questionnaire and have their height and weight measured. For the experimental visit participants will rest in a supine position on a comfortable hospital bed in a custom built airtight box up to the level of the iliac crest (i.e. a lower body negative pressure chamber). They will be instrumented for the measurement of brain blood flow (transcranaial Doppler ultrasound), blood pressure (finger photoplethysmography and automated sphygmomanometer), breathing rate (spirometer, gas analyser).

After a 10 min baseline, three experimental conditions will then be undertaken in a randomised order, namely; 1) neurovascular coupling test with no lower body negative pressure, 2) neurovascular coupling test with -20 mmHg lower body negative pressure, and 3) neurovascular coupling test with -40 mmHg lower body negative pressure. Each trial will last 10 min. Trials will be separated by 30 min. Neurovacular coupling will be assessed (5 cycles, of 20 s eyes closed and 40 s of reading) during each trial.

All sessions will be conducted by a University student (registered for a PhD in Exercise Science) and supervised by an Assoc Prof of Physiology. The mode of administration is one-to-one for all activities. A check list will be use to monitor adherence to the intervention.

Intervention code [1] 315177 0
Early detection / Screening
Comparator / control treatment
The "control" treatment is trial 1) described above (i.e., neurovascular coupling test with no lower body negative pressure)
Control group
Active

Outcomes
Primary outcome [1] 320925 0
Posterior cerebral artery blood flow velocity response to visual stimulation (neurovascular coupling response) using transcranial Doppler ultrasound.
Timepoint [1] 320925 0
This outcome (i.e., neurovascular coupling) will be measured three times during the single experimental session. As described in Step 6 and above, it is a 5 min test involving the continuously measured posterior cerebral artery blood flow velocity response to visual stimulation (this is then signal averaged and a peak response obtained). As such. the outcome is measured during each of the three experimental trial.
Secondary outcome [1] 373367 0
Heart rate (electrocardiogram).
Timepoint [1] 373367 0
Assessed continuously throughout the baseline (10 min) and 3 experimental trials (10 min each).
Secondary outcome [2] 373697 0
Blood pressure (finger photoplethysmography, automated sphygmomanometer)
Timepoint [2] 373697 0
Assessed continuously throughout the baseline (10 min) and 3 experimental trials (10 min each).
Secondary outcome [3] 373698 0
Respiration (spirometer, gas analyser).
Timepoint [3] 373698 0
Assessed continuously throughout the baseline (10 min) and 3 experimental trials (10 min each).

Eligibility
Key inclusion criteria
•Healthy individuals
•Not taking any prescription or over-the-counter medications (other than oral contraceptive pill)
•Body mass index < 30 kg/m2
•No history of syncope (fainting)
•Not hypotensive (e.g., have a resting blood pressure >90/60 mmHg)
Minimum age
18 Years
Maximum age
35 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
•Cardiovascular disease (e.g., coronary heart disease, hypertension)
•Severe respiratory disease (e.g., chronic obstructive pulmonary disease)
•Smokers
•Metabolic disease (e.g., type II diabetes)
•Cancer
•Connective tissue or inflammatory disease
•Neurological disease
•Infection or pyrexial illness
•Thyroid disorders
•Hepatic or renal impairment
•Pregnancy
•Underlying medical conditions, which in the opinion of the Investigator place the participant at unacceptably high risk for participating in the study
•Inability to fully or appropriately provide consent

Study design
Purpose of the study
Diagnosis
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Who is / are masked / blinded?



Intervention assignment
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis

Recruitment
Recruitment status
Stopped early
Data analysis
Data analysis is complete
Reason for early stopping/withdrawal
Other reasons/comments
Other reasons
Scientific aims of this physiological study were achieved with smaller number of participants than initially anticipated.
Date of first participant enrolment
Anticipated
2/09/2019
Actual
18/09/2019
Date of last participant enrolment
Anticipated
31/12/2019
Actual
28/11/2019
Date of last data collection
Anticipated
31/01/2020
Actual
31/01/2020
Sample size
Target
11
Accrual to date
Final
11
Recruitment outside Australia
Country [1] 21737 0
New Zealand
State/province [1] 21737 0
Auckland

Funding & Sponsors
Funding source category [1] 303445 0
University
Name [1] 303445 0
University of Auckland
Country [1] 303445 0
New Zealand
Primary sponsor type
University
Name
University of Auckland
Address
Private Bag 92019
Auckland 1142
Country
New Zealand
Secondary sponsor category [1] 303502 0
None
Name [1] 303502 0
Address [1] 303502 0
Country [1] 303502 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 303978 0
Northern B Health and Disability Ethics Committee
Ethics committee address [1] 303978 0
Ministry of Health
133 Molesworth Street
PO Box 5013
Wellington
6011
Ethics committee country [1] 303978 0
New Zealand
Date submitted for ethics approval [1] 303978 0
Approval date [1] 303978 0
17/07/2019
Ethics approval number [1] 303978 0
19/NTB/104

Summary
Brief summary
The role of the sympathetic nervous system in the regulation of brain blood flow in humans remains controversial and incompletely understood. There is some evidence from human studies that activation of the sympathetic nerves can reduce brain blood flow and/or constrict brain blood vessels. We will test the hypothesis that the sympathetic nervous system modifies the brain blood flow responses to neuronal activation by visial stimulation (known as neurovascular coupling). These investigations will provide new insights into brain blood flow regulation in healthy individuals, with broader implications to relevant patient groups (e.g., people with high blood pressure).
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 95438 0
A/Prof James P Fisher
Address 95438 0
Faculty of Medical and Health Sciences
Department of Physiology
University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 95438 0
New Zealand
Phone 95438 0
+6493737599
Fax 95438 0
Email 95438 0
[email protected]
Contact person for public queries
Name 95439 0
James P Fisher
Address 95439 0
Faculty of Medical and Health Sciences
Department of Physiology
University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 95439 0
New Zealand
Phone 95439 0
+6493737599
Fax 95439 0
Email 95439 0
[email protected]
Contact person for scientific queries
Name 95440 0
James P Fisher
Address 95440 0
Faculty of Medical and Health Sciences
Department of Physiology
University of Auckland
85 Park Road
Grafton
Auckland 1023
Country 95440 0
New Zealand
Phone 95440 0
+6493737599
Fax 95440 0
Email 95440 0
[email protected]

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment
There is no plan to make individual participant data available. Enquires may be send to Principal Investigators via email.


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.