The Combined Influence of Hemorrhage and Ischemia/Reperfusion Injury (I/R) on Muscle Function in Rats

During trauma, tourniquet use is preceded by significant blood loss. The purpose of the present study was to compare tourniquet (TK) induced I/R in skeletal muscle with and without prior hemorrhage (H) in muscles of predominantly different fiber types. Methods Male Sprague‐Dawley rats were assigned to 3 groups (N=6/gp); 1) +H/+TK, 2) −H/+TK, and 3) –H/−TK (sham). Anesthetized rats underwent catheterization of the left carotid artery prior to treatment. +H/+TK and +H/−TK rats were hemorrhaged (33% of total volume) followed immediately by 4 hr. TK application. Isometric measurements were made 2 weeks later on the predominantly fast‐twitch Plantaris muscle and predominantly slow‐twitch Soleus muscle. Results Peak Tetanic Tension (Po) – Percent of ShamConclusion 1) TK results in reduction in absolute and specific Po which is greater in the Plantaris; 2) H prior to TK exacerbated the loss of Po (N, N/cm²) in the Plantaris but not the Soleus; 3) H prior to TK selectively affects fast‐twitch muscle.