Estrogen Effects after a Crush Muscle Injury and Acute Exposure to Hypobaric Hypoxia.

摘要

Aeromedical evacuation, also known as en route care, is a critical and successful strategy for treating soldiers wounded on the battlefield. However, because the aeromedical platform maintains a cabin pressure equivalent to an altitude of 8,000 feet, which is considered high altitude, and lacks abundant supplemental oxygen systems, en route care exposes wounded soldiers to low oxygen content. To ensure wounded soldiers experience a complete recovery, a greater understanding of the effects of hypobaric hypoxia (HH) on injured or damaged tissue is important. The overall objectives of this 4-year project were to (a) create experimental models for studying the effect of HH on muscle recovery and (b) test the effect of estrogen, as a countermeasure, on HH effects on muscle recovery. The major results were as follows: (a) a single exposure to HH for 8-9 hours did not activate the genes and cells of inflammation in healthy skeletal muscle; (b) after an acute closed crush muscle injury, which induced significant inflammation alone, exposure to HH for 8-9 hours led to a reduction in a specific subpopulation of white blood cells, macrophages, at 32 hours post-injury; and (c) estrogen did not counteract the suppressive effect of HH on white blood cells, but did upregulate muscle-specific factors. In conclusion, the occurrence of en route care at 24 hours after an acute muscle injury may hinder the inflammatory response. Although estrogen may not be an effective countermeasure for this response, estrogen may promote muscle regeneration.