Analysis of Local and Circulating Compounds Released Following Blood Pressure Cuff Inflation

This study aims to analyze the way the human body responds to a temporary lack of oxygen, or ischaemia. Prospective participants will complete a health screen to confirm overall health / low cardiovascular risk profile.The participants will be required to have pneumatic blood pressure cuff inflation to 200mmHg on the upper arm for 5 minutes which will then be deflated for 5 minutes and then repeating the cycle of inflation and deflation a further 3 times. Blood tests from veins in the forearm would be taken before, during, and after this is done in order to compare results and establish any change in concentration of local and circulating compounds.

Evidence exists that short periods of ischaemia (lack of oxygen delivered to tissue in the body) can protect a local or remote area of the body from subsequent prolonged periods of serious ischaemia. It has been shown that substances are released into the circulation after short periods of ischaemia that may cause this protection. This study aims to identify some of these compounds.

After participants are informed about the study and have an opportunity to ask questions, informed consent will be obtained. Following this, a modified Exercise and Sports Science Australia questionnaire and brief medical history will be obtained. Blood pressure readings, height, weight and waist circumference would be measured. This is to establish a picture of overall general health and cardiovascular risk profile.

Those who meet the study eligibility criteria will proceed on a subsequent day to the blood pressure cuff inflation protocol. Consumption of caffeine or alcohol cannot be consumed within 4 hours prior to the protocol and participants must minimise any physical activity in the 4 hours prior to the protocol. After resting for 15 minutes on arrival, a baseline venous blood test will be taken from the dominant arm. A standard pneumatic blood pressure cuff will be placed around the non-dominant upper arm and inflated to 200mmHg for 5 minutes. The cuff will then be deflated completely for 5 minutes. This cycle will be repeated a further 3 times, with each cycle commencing as soon as the previous one has been completed. At the end of the final deflation, a second venous blood sample will be taken from the arm with the cuff. 10 minutes after this, a final venous blood test will be taken from the dominant arm. Blood samples will be processed and stored appropriately until analysed by mass spectrometry. Changes in compounds in the cuffed limb and the opposite limb from the baseline blood sample will be analysed.

Eligibility Criteria:
Inclusion Criteria:

* healthy with no known chronic medical conditions
* low cardiovascular risk
* no recent significant illness or injury
* able to provide informed consent

Exclusion Criteria:

* pregnancy or breastfeeding
* moderate or high cardiovascular risk
* chronic medical condition
* taking regular or recent medication, including herbal remedies, recreational drugs or over-the-counter medication
* smoking within the previous 12 months
* previous or current vascular disorders including deep vein thrombosis
* bleeding disorders