The Influence of Cerebral Blood Flow and PETCO2 on Neuromuscular Function During Passive Heat Stress

Brock University

Status and phase: Completed; Phase 4

Conditions: Healthy Males; Neuromuscular Function

Treatments: Drug: Placebo; Drug: Indomethacin

Study type: Interventional

Funder types: Other

Identifiers

NCT01848665

EEL 073.3

Details and patient eligibility

About

Increased core temperature (hyperthermia) has been associated with impaired neuromuscular performance; however, the mechanisms associated with these performance decrements and their potential synergies 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 alkalosis (estimated by end-tidal partial pressure of carbon dioxide; PETCO2) remains unexamined. In response to hyperthermia, humans hyperventilate as means of heat dissipation, resulting in a hypocapnia (reduced PETCO2) mediated decrease in CBF and consequently, cerebral alkalosis (increased cerebral pH). 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 decreased PETCO2 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 passive heat stress. The research project will consist of 3 separate experimental trials: (a) poikilocapnic hyperthermia (increased core temperature; decrease CBF; decrease PETCO2), (b) isocapnic hyperthermia (increased core temperature; no change CBF; no change PETCO2) and (c) isocapnic hyperthermia + indomethacin (increased core temperature; decrease CBF; no change PETCO2). During each manipulation, neuromuscular function will be evaluated and compared to baseline (normothermic) conditions using a repeated measures design.

It is hypothesized that changes in PETCO2 and therefore, changes in cerebral alkalosis will contribute to neuromuscular fatigue independent of changes in CBF or increases in core temperature.

Enrollment: 8 patients

Sex: Male

Ages: 18 to 45 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• 18 to 45 yrs old; healthy males

Exclusion criteria

• diagnosed medical condition; NSAID allergy; smoker; high altitude exposure; implants

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Single Group Assignment

Masking: Single Blind

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8 participants in 2 patient groups, including a placebo group

Drug

Experimental group

Description:

Indomethacin, 1.2 mg kg 1 dose

Treatment:

Drug: Indomethacin

Placebo

Placebo Comparator group

Description:

generic flour placebo capsule

Treatment:

Drug: Placebo