The Effects of Acute Melatonin Supplementation on Cardiovascular Responses to Sympathetic Activation
试验速览
- 阶段
- 4 期
- 状态
- 招募中
- 入组人数
- 100
- 试验地点
- 2
- 主要终点
- Mean Arterial Pressure
研究概览
简要总结
the purpose of this experiment is to determine if acute melatonin supplementation alters central and peripheral cardiovascular responses to a cold pressor test at rest and during dynamic exercise.
详细描述
After IRB approval, experiments will take place in the Human Circulation Research Laboratory in the Department of Health and Exercise on the University of Oklahoma Norman campus. All subjects will complete a total of 3 visits. The first is a screening visit to provide informed consent and to ensure the potential participant meets all inclusion criteria and no exclusion criteria. Once consented and enrolled, participants will be familiarized with experimental protocols. On separate days (visits 2 and 3), participants will complete placebo (PLA) and melatonin (MEL) in a randomly ordered, single-blind, counter-balanced design. PLA or MEL treatment will precede testing by 30min to maximize absorption into the circulation (Bartoli, 2013).
All experiments (PLA/MEL) will begin with the subject lying supine for 5 min of quiet rest where baseline measurements are taken, followed by activation of the lower body negative pressure (LBNP) device causing suction at -20 mmHg. Following LBNP participants will be given 10 minutes of rest to recover all variables to pre-LBNP values. After which participants will be given a hand grip dynamometer to complete 7 minutes of exercise at an intensity of 20% MVC at a 1s contraction to 2s relaxation cycle paced by a metronome. During the final 2 minutes of the 7 minutes of exercise the LBNP device will be activated again to -20mmHg such that the participant will be completing LBNP during rhythmic grip exercise. After the completion of exercise, the subject will remain supine for 10min. Then the a Total Labile Signal (TLS) procedure will be conducted. Where the experimental limb is occluded using a blood pressure cuff for 5min. The cuff is then rapidly deflated. The lowest oxyhemoglobin measured during the occlusion is recorded. After the TLS procedure, the subject will be de-instrumented and will leave the laboratory.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Single (Participant)
盲法说明
Participants will be blinded in two trials. Practitioners and operators will not be allowed to communicate with the participants concerning whether they are receiving placebo/melatonin. Outcome assessors and statisticians may not be blinded to experimental allocation. Our placebo should satisfy two conditions of an ideal placebo: a) it should be indistinguishable from the experimental supplement to blinded participants, and b) it should be physiologically inert. In this study, 1 microliter McCormicks Pure Mint Extract will be mixed with 29 ml of filtered water and given to participants as a sublingual spray. This mixture will be non-caloric and will mimic the taste and sensation of the commercially available melatonin spray that will be used in the study (Onnit Labs Inc., Mint Flavor).
入排标准
- 年龄范围
- 18 Years 至 35 Years(Adult)
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Healthy men and women
- •Women must be premenopausal with a regular menstrual cycle (26-30 days)
排除标准
- •History of autonomic dysfunction
- •Cardiovascular diseases
- •Tobacco/nicotine use
- •Systolic Pressure >= 130 mmHg
- •Diastolic Pressure >= 85 mmHg
- •Regular melatonin use >= 1 use/week
- •Allergy to melatonin
- •Cardiometabolic medication use (e.g. anti-hypertensives, insulin-sensitizing, statins)
- •Sex hormone replacement medical use (e.g. testosterone, estrogen, progesterone)
- •Pregnancy
结局指标
主要结局
Mean Arterial Pressure
时间窗: 7 minutes of rest and 7 minutes of exercise
average pressure within the arteries
Muscle Tissue Oxygenation
时间窗: 7 minutes of rest and 7 minutes of exercise
Concentrations of Total, Oxy, and deoxyhemoglobin of Flexor Digitorum Profundus muscle of the forearm
次要结局
- Cardiac Output(7 minutes of rest and 7 minutes of exercise)
- Cerebral Oxygenation(7 minutes of rest and 7 minutes of exercise)
- Heart Rate(7 minutes of rest and 7 minutes of exercise)
- Respiratory Rate(7 minutes of rest and 7 minutes of exercise)
- Stroke Volume(7 minutes of rest and 7 minutes of exercise)
- Total peripheral resistance(7 minutes of rest and 7 minutes of exercise)
- Heart Rate Variability(7 minutes of rest and 7 minutes of exercise)
