Cerebral Blood Flow and PETCO2 on Neuromuscular Function During Environmental Stress
The Influence of Cerebral Blood Flow and Alkalosis on Neuromuscular Function During Environmental Stress
Environmental stress, such as low oxygen availability (hypoxia), has been associated with impaired neuromuscular performance; however, the mechanisms associated with these performance decrements remain unclear. While the majority of research suggests that the observed fatigue is related to the central nervous system, the influence of changes in cerebral blood flow (CBF) and associated changes in cerebral pH (partial pressure of carbon dioxide; PCO2) remains unexamined. In response to hypoxic stress, humans hyperventilate to maintain oxygen consumption, resulting in a hypocapnia mediated decrease in CBF and cerebral alkalosis (decreased PCO2). Previous research suggests that hyperventilation induces changes in neural excitability and synaptic transmission; however, it remains unclear if these changes are related to hypocapnia mediated decrease in CBF or cerebral alkalosis or both.
The purpose of the proposed research program is to examine the influence of changes in CBF and cerebral alkalosis on neuromuscular function during environmental stress. The research program will consist of 2 separate projects, summarized below in a table outlining the proposed protocols and resultant physiological manipulations. During each manipulation, neuromuscular function will be evaluated and compared to baseline (normoxic) conditions using a repeated measures design.
The research program will consist of 2 separate projects. Project 1 will examine the changes in CBF and alkalosis by using (a) indomethacin (decrease CBF; no change PCO2) and (b) hypocapnia (decrease CBF; decrease PCO2). Using a similar experimental design, Project 2 will examine the change in CBF and alkalosis during hypoxia by using (a) poikilocapnic hypoxia (decrease PO2; decrease CBF; decrease PCO2), (b) isocapnic hypoxia (decrease PO2; no change CBF; no change PCO2) and (c) isocapnic hypoxia + indomethacin (decrease PO2; decrease CBF; no change PCO2). During each manipulation, neuromuscular function will be evaluated and compared to baseline (normoxic) conditions using a repeated measures design.
Therefore, Project 1 will examine the separate and combined effect of changes in CBF and cerebral alkalosis on neuromuscular function independent of environmental manipulations. Subsequently, Project 2 will examine neuromuscular function during hypoxia while controlling CBF and cerebral alkalosis. It is hypothesized that changes in PCO2 and therefore, changes in cerebral alkalosis will contribute to neuromuscular fatigue independent of changes in CBF and oxygen availability.
연구 개요
연구 유형
등록 (실제)
단계
- 4단계
연락처 및 위치
연구 장소
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Ontario
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St Catharines, Ontario, 캐나다, L2S 3A1
- Brock University
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참여기준
자격 기준
공부할 수 있는 나이
건강한 자원 봉사자를 받아들입니다
연구 대상 성별
설명
Inclusion Criteria:
- 18 to 25 yrs old; healthy males
Exclusion Criteria:
- diagnosed medical condition; NSAID allergy; smoker; high altitude exposure; implants
공부 계획
연구는 어떻게 설계됩니까?
디자인 세부사항
- 주 목적: 기초 과학
- 할당: 무작위
- 중재 모델: 단일 그룹 할당
- 마스킹: 하나의
무기와 개입
참가자 그룹 / 팔 |
개입 / 치료 |
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실험적: Drug
Indomethacin 1.2 mg kg 1 dose
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위약 비교기: Placebo
flour capsule
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연구는 무엇을 측정합니까?
주요 결과 측정
결과 측정 |
측정값 설명 |
기간 |
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휴식 모터 임계값
기간: 기준 90분에서 변경
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운동 유발 전위는 운동 피질의 경두개 자기 자극 후 근육에서 기록됩니다.
휴식 모터 임계값은 모터 유발 전위를 유도하는 데 필요한 최소 자극 강도로 정의됩니다.
정지 모터 임계값은 밀리볼트 단위로 정량화됩니다.
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기준 90분에서 변경
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최대 자발적 수축
기간: 기준 90분에서 변경
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최대 자발적 수축(MVC) 테스트 중에 참가자의 오른팔은 전완 굴곡을 격리하고 요측수근 굴근에 의한 힘 생성을 측정하는 데 사용되는 맞춤형 장치에 고정됩니다.
참가자는 5초 MVC를 생성해야 하며 수축 기간 동안 최대 힘 생산을 유지하도록 구두로 권장됩니다.
MVC는 뉴턴 미터 단위의 최대 힘 생산으로 정량화됩니다.
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기준 90분에서 변경
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H-Reflex Amplitude
기간: Change from baseline 90-minutes
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The H-Reflex is an indirect measure of motor neuron excitability.
Initially, a maximal M-wave (M-max) will be elicited by stimulating (1 ms in duration; 15 s between stimuli) the median nerve incrementally (2 V increments) until the largest waveform is observed.
The peak-to-peak amplitude of this waveform is considered M-max.
Using similar procedures as above, a sub-maximal M-wave of 5% M-max will be elicited and the amplitude of the resultant H-reflex (a small waveform observed following the submaximal M-wave) will be calculated.
The amplitude of the H-reflex will be quantified in milllivolts.
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Change from baseline 90-minutes
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H-reflex latency
기간: Change from baseline 90-minutes
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The H-Reflex is an indirect measure of motor neuron excitability.
Initially, a maximal M-wave (M-max) will be elicited by stimulating (1 ms in duration; 15 s between stimuli) the median nerve incrementally (2 V increments) until the largest waveform is observed.
The peak-to-peak amplitude of this waveform is considered M-max.
Using similar procedures as above, a sub-maximal M-wave of 5% M-max will be elicited and the amplitude of the resultant H-reflex (a small waveform observed following the submaximal M-wave) will be calculated.
The onset latency of the H-reflex will be quantified in milliseconds.
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Change from baseline 90-minutes
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Voluntary Activation
기간: Change from baseline 90-minutes
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The level of neural drive to muscle during contraction is termed voluntary activation and will be estimated by interpolation of a single supramaximal motor evoked potential during the 5-second MVC contraction.
If extra force is evoked by the 'superimposed' stimulus then either the stimulated axons were not all recruited voluntarily or they were discharging at sub-tetanic rates.
Therefore, voluntary activation will be quantified as the amplitude of maximal voluntary force production, relative to the amplitude of the supramaximal MEP.
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Change from baseline 90-minutes
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2차 결과 측정
결과 측정 |
측정값 설명 |
기간 |
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중간 대뇌 동맥 혈류 속도
기간: 기준 90분에서 변경
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중간 대뇌 동맥(MCA) 혈류 속도는 2MHz 경두개 도플러(TCD) 초음파 프로브에 의해 비침습적으로 측정되며, 편안한 헤드밴드에 양측으로 부착되고 귓바퀴의 입쪽인 광대뼈 앞쪽에 고정됩니다.
도플러 프로브는 측두 창(귀 근처)을 통해 진행되며 실험 프로토콜 기간 동안 제자리에 유지됩니다.
MCA 속도는 cm/s로 정량화됩니다.
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기준 90분에서 변경
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Brachial Artery Blood flow
기간: Change from baseline 90-minutes
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Brachial artery blood flow will be measured non-invasively using a high-resolution ultrasound machine.
Participants will lie supine with their forearm extended in a comfortable position.
Blood flow measurements will be taken in the top 1/3 of the upper arm over the duration of 10 cardiac cycles (approximately 60 seconds).
Blood flow will be quantified in L/min.
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Change from baseline 90-minutes
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Internal Carotid Artery Blood Flow
기간: Change from baseline 90-minutes
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Internal carotid artery (ICA) blood flow will be measured non-invasively using a high-resolution ultrasound machine.
Participants will lie supine with a slight extension of the neck and at 45° of lateral flexion away from the side being scanned.
ICA measurements will be taken 1 cm superior to the common carotid bifurcation over the duration of 10 cardiac cycles (approximately 60 seconds).
Blood flow will be quantified in L/min.
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Change from baseline 90-minutes
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Blood pressure
기간: Change from baseline 90-minutes
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Beat by beat blood pressure will be calculated from the blood pressure waveform using finger photoplethysmography (Nexfin, bmeye), with a finger cuff placed directly over the middle finger on the left hand.
Blood pressure will be quantified in mmHg.
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Change from baseline 90-minutes
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Pulse oximetry
기간: Change from baseline 90-minutes
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A pulse oximetry probe will be placed over a finger to provide a continuous, non-invasive measurement of the blood oxygen saturation to confirm that the end-tidal forcing system is controlling oxygen delivery at the desired levels during each experiment.
Oxygen saturation will be quantified as a percentage.
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Change from baseline 90-minutes
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Heart Rate
기간: Change from baseline 90-minutes
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Heart rate will be measured by electrocardiogram.
Heart rate will be quantified in beats per minute.
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Change from baseline 90-minutes
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End-Tidal Gas Concentrations
기간: Change from baseline 90-minutes
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The end-tidal concentrations of oxygen and carbon dioxide will be measured and reported in mmHg.
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Change from baseline 90-minutes
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공동 작업자 및 조사자
스폰서
수사관
- 수석 연구원: Stephen Cheung, PhD, Brock University
연구 기록 날짜
연구 주요 날짜
연구 시작
기본 완료 (실제)
연구 완료 (실제)
연구 등록 날짜
최초 제출
QC 기준을 충족하는 최초 제출
처음 게시됨 (추정)
연구 기록 업데이트
마지막 업데이트 게시됨 (실제)
QC 기준을 충족하는 마지막 업데이트 제출
마지막으로 확인됨
추가 정보
이 연구와 관련된 용어
추가 관련 MeSH 약관
기타 연구 ID 번호
- 12-167
이 정보는 변경 없이 clinicaltrials.gov 웹사이트에서 직접 가져온 것입니다. 귀하의 연구 세부 정보를 변경, 제거 또는 업데이트하도록 요청하는 경우 register@clinicaltrials.gov. 문의하십시오. 변경 사항이 clinicaltrials.gov에 구현되는 즉시 저희 웹사이트에도 자동으로 업데이트됩니다. .