REDOX MODULATION OF MUSCLE FUNCTION IN MICROGRAVITY

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Specific Aim: To evaluate NAC as a countermeasure for handgrip fatigue in humans. N-acetylcysteine (NAC; reduced thiol donor) has been shown to inhibit human muscle fatigue in several recent studies. Experiments in healthy volunteers will optimize the preparation and dosage of oral NAC administration and will test NAC effects on handgrip strength and handgrip fatigue during concentric exercise. Hypothesis 1. Oral NAC administration can increase blood thiol levels and inhibit exercise-induced oxidative stress without undesirable side effects. Five NAC doses and two preparations, solution or capsule, will be tested to optimize glutathione protection and minimize side effects. Hypothesis 2. NAC pretreatment delays task failure during concentric handgrip exercise. The most effective NAC administration protocol from Expt. 1 will be tested for its capacity to delay fatigue during a standardized protocol of volitional handgrip exercise.