Cold stress does not induce stress proteins SP 25 and SP 72 in rat skeletal muscle

Cryotherapy is a common treatment for musculoskeletal injuries, yet the mechanism(s) underlying its effects remain unclear. Since cryotherapeutic treatment often involves temperatures that are known to induce the protective stress proteins (SPs), we determined whether SP 25 and SP 72 expression was altered following a 20-min cold stress to the hindlimb muscles of Sprague-Dawley rats. The right hindlimb of anesthetized animals was placed in an ice bath until muscle temperature decreased to either 8.4 +/- 0.4 degrees C or 19.7 +/- 0.3 degrees C for 20 min. After a 24-h recovery, the white and red gastrocnemius, plantaris, soleus, extensor digitorum longus, and tibialis anterior muscles from both legs were removed and rapidly frozen in liquid nitrogen. Portions of the muscles were homogenized and SP 25 and SP 72 content was assessed by SDS-PAGE/Western blot analyses. Quantification of SP 25 and SP 72 by densitometric scanning of blots demonstrated no significant increases in SP 25 or SP 72 content in any of the muscles exposed to either the 8 or the 20 degrees C cold stress compared to muscles from the unstressed contralateral limbs. These results suggest that a 20-min cold stress of 8 degrees C or 20 degrees C does not increase muscle SP 25 or SP 72 content.