The effects of burn trauma on adenosine 3':5' cyclic monophosphate, inositol trisphosphate, and contraction in mouse gastrocnemius muscle.

This study examines the nature of skeletal muscle weakness (dysfunction) that is exhibited by patients who have incurred large-size body surface area burns (greater than 30%). It uses the mouse model of scald-burn injury in which groups of mice with varying burn sizes (i.e., 20%, 30%, and 50%) and time-matched controls were evaluated on postburn day 21. The primary purpose of this work was to evaluate secondary messenger cascades in gastrocnemius muscle relative to increasing burn size. Muscles that were distantly located to the actual site of burn injury were used for twitch analyses to measure active tension. The second messengers, adenosine 3':5' cyclic monophosphate (cAMP), inositol, 1,4,5-trisphosphate (IP3) and Ca2+, were measured with radioisotopes. The results of this study indicate that perturbations in the cAMP-IP3 cascade may be responsible for increasing myoplasmic Ca2+, which leads to dysfunction. The long-term goal of this work is to aid in the alleviation of chronic skeletal muscle dysfunction that leads to sustained debilitation and prolonged rehabilitation in patients with burns.